AlgoDaily - Reverse a String

With two pointers, we've cut the number of operations in half. It's much faster now! However, similar to the brute force, the time complexity is still O(n).

Why Is This?

Well, if n is the length of the string, we'll end up making n/2 swaps. But remember, Big O Notation isn't about the raw number of operations required for an algorithm-- it's about how the number scales with the input.

So despite requiring half the number operations-- a 4-character string would require 2 swaps with the two-pointer method. But an 8-character string would require 4 swaps. The input doubled, and so did the number of operations.

If you haven't by now, try to do the problem before moving on.

xxxxxxxxxx
​
 
var assert = require('assert');
​
function reverseString(str) {
  // reverse str
  return str;
}
​
try {
  assert.equal(
    reverseString('njnschnjkdasn j32 uida'),
    'adiu 23j nsadkjnhcsnjn'
  );
​
  console.log(
    'PASSED: ' +
      "`reverseString('njnschnjkdasn j32 uida')` should return `'adiu 23j nsadkjnhcsnjn'`"
  );
} catch (err) {
  console.log(err);
}
​
try {
  assert.equal(reverseString('timbuktu12'), '21utkubmit');
​
  console.log(
    'PASSED: ' + "`reverseString('timbuktu12')` should return `'21utkubmit'`"
  );

OUTPUT

Results will appear here.