Welcome to the introduction of hash tables in the Hash Tables tutorial! In this lesson, we will explore the concept of hash tables, a data structure that allows for efficient retrieval and storage of key-value pairs.
Hash tables provide fast access to data by using a technique called hashing. Hashing involves applying a hash function to a key to compute an index or address where the value is stored.
To understand hash tables, let's start with a basic analogy. Imagine you have a large library with thousands of books. Each book is assigned a unique identification number based on its title. When you want to find a specific book, you can quickly locate it by searching for its identification number.
Similarly, in a hash table, the keys are like book titles, and the hash function converts the keys into unique index values. This process allows for constant-time operations like insertion, retrieval, and deletion.
A hash table consists of two main components: an array and a hash function. The array is used to store the values, while the hash function maps the keys to their corresponding array indices.
Let's take a look at a simple example to understand this concept better:
1class Main {
2 public static void main(String[] args) {
3 // Create a hash table
4 HashTable<String, Integer> hashTable = new HashTable<>();
5
6 // Insert key-value pairs
7 hashTable.insert("Alice", 24);
8 hashTable.insert("Bob", 32);
9 hashTable.insert("Charlie", 41);
10
11 // Retrieve values
12 int age1 = hashTable.get("Alice");
13 int age2 = hashTable.get("Bob");
14 int age3 = hashTable.get("Charlie");
15
16 System.out.println("Alice's age: " + age1);
17 System.out.println("Bob's age: " + age2);
18 System.out.println("Charlie's age: " + age3);
19 }
20}Try this exercise. Is this statement true or false?
Hash tables use a hashing function to compute an index where the value is stored.
Press true if you believe the statement is correct, or false otherwise.
To implement a hash table, we first need to set up a hash table class and then instantiate it in code. Let's start by creating a HashTable class in Java:
1class HashTable<K, V> {
2
3 private static final int SIZE = 10;
4
5 private Entry<K, V>[] buckets;
6
7 public HashTable() {
8 this.buckets = new Entry[SIZE];
9 }
10
11 // Other methods
12}In the HashTable class, we have defined a generic type K for the key and V for the value. We have also created a fixed-size array buckets to store the key-value pairs.
To insert a key-value pair into the hash table, we need to calculate the index using a hash function. For simplicity, let's use the built-in hashCode() method of the key object and take the modulus of it with the size of the array. Here's the implementation of the insert() method:
1public void insert(K key, V value) {
2 int index = getIndex(key);
3
4 Entry<K, V> newEntry = new Entry<>(key, value);
5
6 if (buckets[index] == null) {
7 buckets[index] = newEntry;
8 } else {
9 Entry<K, V> currentEntry = buckets[index];
10 while (currentEntry.next != null) {
11 if (currentEntry.key.equals(key)) {
12 currentEntry.value = value;
13 return;
14 }
15 currentEntry = currentEntry.next;
16 }
17 currentEntry.next = newEntry;
18 }
19}The insert() method first calculates the index using the getIndex() helper method. If the bucket at the calculated index is empty, it simply stores the new key-value pair there. Otherwise, it iterates through the linked list at the bucket to find the key. If the key is found, it updates the value. If the key is not found, it adds the new key-value pair at the end of the linked list.
To retrieve a value based on a key from the hash table, we use the get() method. Here's the implementation:
1public V get(K key) {
2 int index = getIndex(key);
3
4 if (buckets[index] == null) {
5 return null;
6 }
7
8 Entry<K, V> currentEntry = buckets[index];
9 while (currentEntry != null) {
10 if (currentEntry.key.equals(key)) {
11 return currentEntry.value;
12 }
13 currentEntry = currentEntry.next;
14 }
15
16 return null;
17}The get() method first calculates the index using the getIndex() method. If the bucket at the calculated index is empty, it returns null. Otherwise, it iterates through the linked list at the bucket to find the key. If the key is found, it returns the corresponding value. If the key is not found, it returns null.
To delete a key-value pair from the hash table, we use the remove() method. Here's the implementation:
1public void remove(K key) {
2 int index = getIndex(key);
3
4 if (buckets[index] == null) {
5 return;
6 }
7
8 if (buckets[index].key.equals(key)) {
9 buckets[index] = buckets[index].next;
10 return;
11 }
12
13 Entry<K, V> currentEntry = buckets[index];
14 Entry<K, V> prevEntry = null;
15
16 while (currentEntry != null) {
17 if (currentEntry.key.equals(key)) {
18 prevEntry.next = currentEntry.next;
19 return;
20 }
21 prevEntry = currentEntry;
22 currentEntry = currentEntry.next;
23 }
24}The remove() method first calculates the index using the getIndex() method. If the bucket at the calculated index is empty, it simply returns. If the first entry in the linked list at the bucket matches the key, it updates the bucket to skip the first entry. Otherwise, it iterates through the linked list to find the key. If the key is found, it updates the previous entry's next reference to skip the current entry, effectively removing it. If the key is not found, it simply returns.
Now that we have implemented the basic functionality of a hash table, let's test it out with some example code:
1public static void main(String[] args) {
2 HashTable<String, Integer> hashTable = new HashTable<>();
3
4 hashTable.insert("Alice", 24);
5 hashTable.insert("Bob", 32);
6 hashTable.insert("Charlie", 41);
7
8 int age1 = hashTable.get("Alice");
9 int age2 = hashTable.get("Bob");
10 int age3 = hashTable.get("Charlie");
11
12 System.out.println("Alice's age: " + age1);
13 System.out.println("Bob's age: " + age2);
14 System.out.println("Charlie's age: " + age3);
15
16 hashTable.remove("Bob");
17 System.out.println("Bob's age after removal: " + hashTable.get("Bob"));
18}The code creates a HashTable instance and inserts three key-value pairs. It then retrieves the ages of Alice, Bob, and Charlie using the get() method and prints them. Finally, it removes the entry for Bob and tries to retrieve his age again, which should return null.
Congratulations! You have implemented a basic hash table that supports insertion, retrieval, and deletion of key-value pairs.
xxxxxxxxxx}public class HashTable<K, V> { private static final int SIZE = 10; private Entry<K, V>[] buckets; public HashTable() { this.buckets = new Entry[SIZE]; } public void insert(K key, V value) { int index = getIndex(key); Entry<K, V> newEntry = new Entry<>(key, value); if (buckets[index] == null) { buckets[index] = newEntry; } else { Entry<K, V> currentEntry = buckets[index]; while (currentEntry.next != null) { if (currentEntry.key.equals(key)) { currentEntry.value = value; return; } currentEntry = currentEntry.next; } currentEntry.next = newEntry; } }Build your intuition. Fill in the missing part by typing it in.
To implement a hash table, we first need to set up a hash table class and then instantiate it in ___.
Write the missing line below.
To implement a hash table, we need to understand the concept of hashing. Hashing is a technique that maps data to a fixed-size array called a hash table using a hashing function. The hashing function takes the data as input and produces a unique numeric value called a hash code. This hash code serves as the index where the data will be stored in the hash table.
For example, let's consider a hash table with 10 buckets. We want to store a key-value pair {"name": "John"}. To determine the index for this pair, we apply a hashing function to the key "name". The hashing function returns a hash code, let's say 123456. We then take the modulus of this hash code with the size of the hash table (10), which gives us the index 6. So, the key-value pair {"name": "John"} will be stored in bucket 6 of the hash table.
Here's an example implementation of a hashing function in Java:
xxxxxxxxxximport java.util.ArrayList;class HashTable<K, V> { private static final int SIZE = 10; private ArrayList<Entry<K, V>>[] buckets; public HashTable() { this.buckets = new ArrayList[SIZE]; } private int getIndex(K key) { int hashCode = key.hashCode(); int index = Math.abs(hashCode % SIZE); return index; } // Other methods}Are you sure you're getting this? Fill in the missing part by typing it in.
To implement a hashing function, we need to carefully choose an algorithm that produces a unique hash code for each input. The hash code should be consistent and evenly distributed across the range of possible inputs. One commonly used hashing algorithm is the ___ algorithm.
Write the missing line below.
To insert key-value pairs into a hash table, we need to determine the index where the pair should be stored. We can achieve this by applying a hashing function to the key. The hashing function returns a unique hash code for the key, which we can then use to calculate the index within the hash table.
Here's an example implementation of a put method in Java:
1// Create a HashTable class
2class HashTable {
3 // Define the initial size of the hash table
4 private final int INITIAL_SIZE = 16;
5 // Use an array of HashEntry objects to represent the hash table
6 private HashEntry[] entries;
7
8 // Constructor
9 public HashTable() {
10 entries = new HashEntry[INITIAL_SIZE];
11 }
12
13 // Method to insert key-value pairs into the hash table
14 public void put(String key, String value) {
15 // Calculate the index based on the hash code of the key
16 int index = getIndex(key);
17
18 // Create a new HashEntry object
19 HashEntry entry = new HashEntry(key, value);
20
21 // Check if the index is empty
22 if (entries[index] == null) {
23 entries[index] = entry;
24 } else {
25 // Traverse the chain of entries at the index
26 HashEntry current = entries[index];
27
28 // Check if the key already exists
29 while (current.next != null) {
30 if (current.key.equals(key)) {
31 // Key already exists, update the value
32 current.value = value;
33 return;
34 }
35
36 current = current.next;
37 }
38
39 // Check the last entry
40 if (current.key.equals(key)) {
41 // Key already exists, update the value
42 current.value = value;
43 } else {
44 // Add the new entry to the end of the chain
45 current.next = entry;
46 }
47 }
48 }
49
50 // Method to retrieve the value associated with a key from the hash table
51 public String get(String key) {
52 // Calculate the index based on the hash code of the key
53 int index = getIndex(key);
54
55 // Traverse the chain of entries at the index
56 HashEntry current = entries[index];
57
58 // Check if the key exists
59 while (current != null) {
60 if (current.key.equals(key)) {
61 return current.value;
62 }
63
64 current = current.next;
65 }
66
67 return null;
68 }
69
70 // Method to calculate the index based on the hash code of the key
71 private int getIndex(String key) {
72 int hashCode = key.hashCode();
73 int index = Math.abs(hashCode) % entries.length;
74
75 return index;
76 }
77
78 // Inner class to represent the entries in the hash table
79 private class HashEntry {
80 private final String key;
81 private String value;
82 private HashEntry next;
83
84 public HashEntry(String key, String value) {
85 this.key = key;
86 this.value = value;
87 this.next = null;
88 }
89 }
90}xxxxxxxxxx}class HashTable { private final int INITIAL_SIZE = 16; private HashEntry[] entries; public HashTable() { entries = new HashEntry[INITIAL_SIZE]; } public void put(String key, String value) { int index = getIndex(key); HashEntry entry = new HashEntry(key, value); if (entries[index] == null) { entries[index] = entry; } else { HashEntry current = entries[index]; while (current.next != null) { if (current.key.equals(key)) { // Key already exists, update value current.value = value; return; } current = current.next; } if (current.key.equals(key)) {Build your intuition. Click the correct answer from the options.
When inserting a new key-value pair into a hash table, which of the following is NOT a best practice?
Click the option that best answers the question.
- Avoid collisions
- Resize the hash table when it reaches a certain load factor
- Use a hashing function with a low collision rate
- Only insert unique keys
To retrieve values from a hash table based on keys, we can implement a get method. This method takes a key as input and returns the corresponding value stored in the hash table.
Here's an example implementation of a get method in Java:
1// Create a HashTable class
2class HashTable {
3 // Define the initial size of the hash table
4 private final int INITIAL_SIZE = 16;
5 // Use an array of HashEntry objects to represent the hash table
6 private HashEntry[] entries;
7
8 // Constructor
9 public HashTable() {
10 entries = new HashEntry[INITIAL_SIZE];
11 }
12
13 // Method to insert key-value pairs into the hash table
14 public void put(String key, String value) {
15 // Calculate the index based on the hash code of the key
16 int index = getIndex(key);
17
18 // Create a new HashEntry object
19 HashEntry entry = new HashEntry(key, value);
20
21 // Check if the index is empty
22 if (entries[index] == null) {
23 entries[index] = entry;
24 } else {
25 // Traverse the chain of entries at the index
26 HashEntry current = entries[index];
27
28 // Check if the key already exists
29 while (current.next != null) {
30 if (current.key.equals(key)) {
31 // Key already exists, update the value
32 current.value = value;
33 return;
34 }
35
36 current = current.next;
37 }
38
39 // Check the last entry
40 if (current.key.equals(key)) {
41 // Key already exists, update the value
42 current.value = value;
43 } else {
44 // Add the new entry to the end of the chain
45 current.next = entry;
46 }
47 }
48 }
49
50 // Method to retrieve the value associated with a key from the hash table
51 public String get(String key) {
52 // Calculate the index based on the hash code of the key
53 int index = getIndex(key);
54
55 // Traverse the chain of entries at the index
56 HashEntry current = entries[index];
57
58 // Check if the key exists
59 while (current != null) {
60 if (current.key.equals(key)) {
61 return current.value;
62 }
63
64 current = current.next;
65 }
66
67 return null;
68 }
69
70 // Method to calculate the index based on the hash code of the key
71 private int getIndex(String key) {
72 int hashCode = key.hashCode();
73 int index = Math.abs(hashCode) % entries.length;
74
75 return index;
76 }
77
78 // Inner class to represent the entries in the hash table
79 private class HashEntry {
80 private final String key;
81 private String value;
82 private HashEntry next;
83
84 public HashEntry(String key, String value) {
85 this.key = key;
86 this.value = value;
87 this.next = null;
88 }
89 }
90}xxxxxxxxxx// Create a HashTable classAre you sure you're getting this? Fill in the missing part by typing it in.
To retrieve values from a hash table based on keys, we can use the get method. This method takes a key as input and returns the corresponding value stored in the hash table.
Here's an example implementation of a get method in Java:
1// Method to retrieve the value associated with a key from the hash table
2public String get(String key) {
3 // Calculate the index based on the hash code of the key
4 int index = getIndex(key);
5
6 // Traverse the chain of entries at the index
7 HashEntry current = entries[index];
8
9 // Check if the key exists
10 while (current != null) {
11 if (current.key.equals(key)) {
12 return current.value;
13 }
14
15 current = current.next;
16 }
17
18 return null;
19}
20
21// ... rest of the codeWrite the missing line below.
To update values stored in a hash table based on keys, we can add a method called updateValue. This method takes a key and a new value as input and updates the value associated with the key in the hash table.
Here's an example implementation of the updateValue method in Java:
1// Create a HashTable class
2class HashTable {
3 // Define the initial size of the hash table
4 private final int INITIAL_SIZE = 16;
5 // Use an array of HashEntry objects to represent the hash table
6 private HashEntry[] entries;
7
8 // Constructor
9 public HashTable() {
10 entries = new HashEntry[INITIAL_SIZE];
11 }
12
13 // Method to insert key-value pairs into the hash table
14 public void put(String key, String value) {
15 // Calculate the index based on the hash code of the key
16 int index = getIndex(key);
17
18 // Create a new HashEntry object
19 HashEntry entry = new HashEntry(key, value);
20
21 // Check if the index is empty
22 if (entries[index] == null) {
23 entries[index] = entry;
24 } else {
25 // Traverse the chain of entries at the index
26 HashEntry current = entries[index];
27
28 // Check if the key already exists
29 while (current.next != null) {
30 if (current.key.equals(key)) {
31 // Key already exists, update the value
32 current.value = value;
33 return;
34 }
35
36 current = current.next;
37 }
38
39 // Check the last entry
40 if (current.key.equals(key)) {
41 // Key already exists, update the value
42 current.value = value;
43 } else {
44 // Add the new entry to the end of the chain
45 current.next = entry;
46 }
47 }
48 }
49
50 // Method to update the value associated with a key in the hash table
51 public void updateValue(String key, String value) {
52 // Calculate the index based on the hash code of the key
53 int index = getIndex(key);
54
55 // Traverse the chain of entries at the index
56 HashEntry entry = entries[index];
57
58 // Check if the key exists
59 while (entry != null) {
60 if (entry.key.equals(key)) {
61 // Key found, update the value
62 entry.value = value;
63 return;
64 }
65
66 entry = entry.next;
67 }
68 }
69
70 // Method to calculate the index based on the hash code of the key
71 private int getIndex(String key) {
72 int hashCode = key.hashCode();
73 int index = Math.abs(hashCode) % entries.length;
74
75 return index;
76 }
77
78 // Inner class to represent the entries in the hash table
79 private class HashEntry {
80 private final String key;
81 private String value;
82 private HashEntry next;
83
84 public HashEntry(String key, String value) {
85 this.key = key;
86 this.value = value;
87 this.next = null;
88 }
89 }
90}xxxxxxxxxx}class HashTable { private final int INITIAL_SIZE = 16; private HashEntry[] entries; public HashTable() { entries = new HashEntry[INITIAL_SIZE]; } public void put(String key, String value) { int index = getIndex(key); HashEntry entry = new HashEntry(key, value); if (entries[index] == null) { entries[index] = entry; } else { HashEntry current = entries[index]; while (current.next != null) { if (current.key.equals(key)) { current.value = value; return; } current = current.next; } if (current.key.equals(key)) { current.value = value;Try this exercise. Fill in the missing part by typing it in.
To update values stored in a hash table based on keys, we can use the method _____________. This method takes a key and a new value as input and updates the value associated with the key in the hash table.
Write the missing line below.
To add the functionality of deleting key-value pairs from the hash table, we can implement a method called delete. This method takes a key as input and removes the entry with the matching key from the hash table.
Here's an example implementation of the delete method in Java:
1<CODE>xxxxxxxxxx}class HashTable { private final int INITIAL_SIZE = 16; private HashEntry[] entries; public HashTable() { entries = new HashEntry[INITIAL_SIZE]; } // Method to delete key-value pairs from the hash table public void delete(String key) { int index = getIndex(key); // Check if the index is empty if (entries[index] == null) { return; } // Check if the first entry matches the key if (entries[index].key.equals(key)) { entries[index] = entries[index].next; return; } // Traverse the chain of entries at the index HashEntry current = entries[index]; HashEntry previous = null; while (current != null) { // Check if the current entry matches the keyBuild your intuition. Fill in the missing part by typing it in.
To delete a key-value pair from a hash table, we need to find the ___ using the hash function and remove it from the corresponding bucket. After removing the entry, we need to handle any possible ___ to maintain the integrity of the hash table. By properly handling collisions, we ensure that all key-value pairs are stored and retrievable in the hash table.
Write the missing line below.
When inserting data into a hash table, it's possible for two different keys to produce the same hash value. This is known as a collision. Handling collisions is an important aspect of hash table implementation.
There are several common collision resolution techniques:
1. Separate Chaining: In this technique, each bucket in the hash table is a linked list. When a collision occurs, the entry with the colliding key is added to the linked list at the corresponding bucket.
Here's an example of using separate chaining to handle collisions in Java:
1// Implementation of hash table with separate chaining
2import java.util.LinkedList;
3
4public class HashTable<K, V> {
5 private int size;
6 private LinkedList<Entry<K, V>>[] buckets;
7
8 public HashTable(int size) {
9 this.size = size;
10 this.buckets = new LinkedList[size];
11 }
12
13 // Other methods omitted for brevity
14}xxxxxxxxxx}```javaimport java.util.LinkedList;public class HashTable<K, V> { private int size; private LinkedList<Entry<K, V>>[] buckets; public HashTable(int size) { this.size = size; this.buckets = new LinkedList[size]; } public void put(K key, V value) { int index = getIndex(key); if (buckets[index] == null) { buckets[index] = new LinkedList<>(); } LinkedList<Entry<K, V>> bucket = buckets[index]; for (Entry<K, V> entry : bucket) { if (entry.key.equals(key)) { entry.value = value; return; } } bucket.add(new Entry<>(key, value)); }Build your intuition. Fill in the missing part by typing it in.
When a collision occurs in a hash table, the entry with the colliding key is added to the linked list at the corresponding _ bucket.
Write the missing line below.
Hash Table Performance Analysis
When analyzing the time and space complexity of hash table operations, it is important to consider the following factors:
Time Complexity:
- Insertion: The time complexity of inserting a key-value pair into a hash table is typically considered to be
O(1)in the average case. However, in the worst case scenario where there are many collisions, the time complexity can beO(n)wherenis the number of elements in the hash table. This is because in the worst case, all elements would be stored in the same bucket and a linear search would be required to find the desired element. - Retrieval: Similar to insertion, the time complexity of retrieving a value based on a key from a hash table is typically considered to be
O(1)in the average case. However, in the worst case scenario with many collisions, the time complexity may beO(n)as explained above. - Update: Updating the value associated with a key in a hash table requires finding the key and replacing its value. This operation has a time complexity of
O(1)in the average case, but can beO(n)in the worst case scenario with many collisions. - Deletion: Deleting a key-value pair from a hash table also has a time complexity of
O(1)in the average case, but can beO(n)in the worst case.
- Insertion: The time complexity of inserting a key-value pair into a hash table is typically considered to be
Space Complexity:
- The space complexity of a hash table is proportional to the number of elements stored in it. In the average case, a hash table has a
O(n)space complexity, wherenis the number of elements. However, in the worst case scenario with many collisions, the space complexity can beO(n^2), wherenis the number of buckets in the hash table.
- The space complexity of a hash table is proportional to the number of elements stored in it. In the average case, a hash table has a
It is important to note that the performance of hash table operations can be greatly influenced by the quality of the hash function used. A good hash function can minimize collisions and therefore improve the overall performance of the hash table. Similarly, choosing an appropriate capacity and load factor can also impact the performance.
Overall, hash tables offer efficient time complexity for insertion, retrieval, update, and deletion operations in the average case. However, in the worst case scenario with many collisions, the performance can degrade.
xxxxxxxxxx}```java// Example of a hash table implementationimport java.util.LinkedList;public class HashTable<K, V> { private int size; private LinkedList<Entry<K, V>>[] buckets; public HashTable(int size) { this.size = size; this.buckets = new LinkedList[size]; } public void put(K key, V value) { int index = key.hashCode() % size; LinkedList<Entry<K, V>> bucket = buckets[index]; if (bucket == null) { bucket = new LinkedList<>(); buckets[index] = bucket; } for (Entry<K, V> entry : bucket) { if (entry.getKey().equals(key)) { entry.setValue(value); return; } }Let's test your knowledge. Is this statement true or false?
Hash tables offer efficient time complexity for insertion, retrieval, update, and deletion operations in the worst case scenario with many collisions. 🤔
Press true if you believe the statement is correct, or false otherwise.
Applications of Hash Tables
Hash tables have various applications in software development and computer science. They provide efficient lookup, insertion, and deletion operations, making them suitable for solving problems where fast key-value pair access is needed. Let's explore some real-world applications of hash tables:
Caching: Hash tables are commonly used in caching systems to store frequently accessed data. By using a hash table, the system can quickly retrieve the cached data without needing to fetch it from the original source.
Database indexing: Hash tables are used in database indexing to achieve fast retrieval of data based on key values. Indexing allows for efficient search operations in large datasets, improving the overall performance of the database.
Symbol tables: Hash tables are used to implement symbol tables in compilers and interpreters. Symbol tables store identifiers (such as variable names) and their associated information, allowing for efficient lookup and manipulation of symbols during the compilation or interpretation process.
Spell checking: Hash tables can be used in spell-checking algorithms to store a dictionary of correctly spelled words. When checking the spelling of a word, the hash table can quickly determine whether the word is valid or not, improving the efficiency of the spell-checking process.
Deduplication: Hash tables are useful for removing duplicates from a collection of data. By inserting elements into a hash table and checking for duplicates using the hash function, duplicate elements can be easily identified and eliminated.
These are just a few examples of how hash tables are applied in real-world scenarios. The flexibility and efficiency of hash tables make them an essential data structure in many areas of software development and computer science.
xxxxxxxxxxclass Main { public static void main(String[] args) { // replace with your Java logic here for(int i = 1; i <= 100; i++) { if(i % 3 == 0 && i % 5 == 0) { System.out.println("FizzBuzz"); } else if(i % 3 == 0) { System.out.println("Fizz"); } else if(i % 5 == 0) { System.out.println("Buzz"); } else { System.out.println(i); } } }}Let's test your knowledge. Is this statement true or false?
Hash tables are commonly used in caching systems to store frequently accessed data.
Press true if you believe the statement is correct, or false otherwise.
Conclusion
In this tutorial, we have explored the concept of hash tables and their applications in computer science and software development. Hash tables provide a fast and efficient way to store and retrieve key-value pairs. They are widely used in various scenarios where quick access to data is required.
Throughout the tutorial, we have covered the following topics:
- Introduction to hash tables
- Implementing a hash table
- Hashing functions
- Inserting, retrieving, updating, and deleting key-value pairs
- Handling collisions
- Performance analysis
- Real-world applications
By understanding these concepts, you now have a solid foundation for using hash tables in your own projects and solving problems efficiently.
If you want to further explore data structures and algorithms, I recommend studying topics like arrays, linked lists, trees, graphs, and sorting algorithms. Additionally, low-level design and high-level design concepts can help you build scalable and efficient software systems.
Keep practicing and applying these concepts in your coding projects. The more you use them, the better you will become at designing and implementing efficient solutions.
Remember, becoming proficient in data structures and algorithms is an ongoing journey. Stay curious, keep learning, and enjoy the process!
xxxxxxxxxximport java.util.HashMap;public class Main { public static void main(String[] args) { // Create a new hash table HashMap<String, Integer> hashTable = new HashMap<>(); // Insert key-value pairs hashTable.put("Apple", 10); hashTable.put("Orange", 5); hashTable.put("Banana", 8); // Retrieve values int numberOfApples = hashTable.get("Apple"); int numberOfOranges = hashTable.get("Orange"); int numberOfBananas = hashTable.get("Banana"); // Update values hashTable.put("Apple", numberOfApples + 1); hashTable.put("Orange", numberOfOranges - 2); hashTable.put("Banana", numberOfBananas + 3); // Delete key-value pairs hashTable.remove("Orange"); // Print the final hash table System.out.println(hashTable); }}Let's test your knowledge. Is this statement true or false?
Hash tables provide a fast and efficient way to store and retrieve key-value pairs.
Press true if you believe the statement is correct, or false otherwise.
Generating complete for this lesson!
