Good morning! Here's our prompt for today.

The Four Musketeers: Finding Quadruplets in an Array

Let's say you have a treasure chest, represented as an array of integers called nums. Your mission, should you choose to accept it, is to find four unique keys (numbers) from this treasure chest that unlock a magical target value when combined.

In other words, you have to find all unique sets of four integers [nums[a], nums[b], nums[c], nums[d]] such that:

• 0 < a, b, c, d < length of array
• a, b, c, and d are distinct.
• nums[a] + nums[b] + nums[c] + nums[d] = target

You can present these sets in any order you like!

Examples to Illuminate the Path

Example 1:

Input: Your treasure chest is [1,0,-1,0,-2,2] and the magical target is 0.
Output: The unique sets of keys that unlock the magical target are [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]].

Example 2:

Input: Your treasure chest is [2,2,2,2,2] and the magical target is 8.
Output: The only set of keys that unlock the magical target is [[2,2,2,2]].

Magical Constraints:

• The treasure chest will have between 1 and 200 keys.
• The value of each key and the magical target will range from -10^9 to 10^9.

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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// Function to find all unique quadruplets that add up to the target sum.

// FILL OUT YOUR SOLUTION HERE

function fourSum(nums, target) {

  // Write your logic here.

}

​

// Utility function to compare two 2D arrays

function are2DArraysEqual(arr1, arr2) {

  if (arr1.length !== arr2.length) return false;

​

  for (let i = 0; i < arr1.length; i++) {

    if (arr1[i].length !== arr2[i].length) return false;

​

    for (let j = 0; j < arr1[i].length; j++) {

      if (arr1[i][j] !== arr2[i][j]) return false;

    }

  }

​

  return true;

}

​

// Test cases to validate your solution

function runTests() {

  // Test Case 1

  let testCase1 = fourSum([1, 0, -1, 0, -2, 2], 0);

  let expected1 = [[-2, -1, 1, 2], [-2, 0, 0, 2], [-1, 0, 0, 1]];  // You can sort the arrays for easier comparison

  console.log("Test Case 1: ", are2DArraysEqual(testCase1, expected1) ? "Passed" : "Failed");

​

  // Test Case 2

Here's how we would solve this problem...

How do I use this guide?