Leetcode Two Sum Problem

Solution for leetcode easy problem "Two Sum"

Suboor Khan
Suboor Khan

Suboor Khan

Software Engineer

TypescriptProblem solving

1. Two Sum

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

 

Example 1:

Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2:

Input: nums = [3,2,4], target = 6
Output: [1,2]

Example 3:

Input: nums = [3,3], target = 6
Output: [0,1]

 

Constraints:

  • 2 <= nums.length <= 104
  • -109 <= nums[i] <= 109
  • -109 <= target <= 109
  • Only one valid answer exists.

 

Follow-up: Can you come up with an algorithm that is less than O(n2time complexity?



Solution

    
        function twoSum(nums: number[], target: number): number[] {
            const hash = {};
            for(let x = 0; x < nums.length; x++) {
                if(hash[nums[x]] !== undefined) {
                    return [hash[nums[x]], x];
                }
                hash[target - nums[x]] = x;
            }
          
            return []
          };
    
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