Leetcode 1: Two Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

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

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

 

public class Solution {
    public int[] TwoSum(int[] nums, int target) {
        var output = new int[2];
        var dict = new Dictionary<int, int>();
        
        for (int i = 0; i < nums.Length; i++)
        {
            if (dict.ContainsKey(target - nums[i]))
            {
                output[0] = dict[target - nums[i]];
                output[1] = i;
                
                return output;
            }
            
            dict[nums[i]] = i;
        }
        
        return output;
    }
}