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Unique Pairs with Target Sum

Unique Pairs with Target Sum

🟢 Easy 🧩 Pattern – Arrays and Hashmap

Given an array of distinct integers and a target sum, return an array of unique pairs of numbers which add up to the target sum. Each pair should be represented as an array containing only two numbers.

Example

Input : [2, 4, 3, 6, 7, 1, 5]
TargetSum : 8
Output : [ [ 6, 2 ], [ 1, 7 ], [ 3, 5 ] ]Code language: CSS (css)

Solution

function targetSumPairs(nums, target) {
  const pairs = [];
  const seen = new Set(); // Acts like a Hashmap

  for (const num of nums) {
    const diff = target - num;
    if (seen.has(diff)) {
      pairs.push([num, diff]);
    } else {
      seen.add(num);
    }
  }
  return pairs;
}

const target = 8;
const nums = [2, 4, 3, 6, 7, 1, 5];
console.log(targetSumPairs(nums, target));
// [[6, 2], [1, 7], [5, 3]]

console.log(targetSumPairs([-1, -2, -3, 1, 2, 3], 0)); 
// Output: [ [ 1, -1 ], [ 2, -2 ], [ 3, -3 ] ]

console.log(targetSumPairs([1, 2, 3, 4, 5], 10));
// Output: []Code language: JavaScript (javascript)
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