Two sum problem ( Without Repeating Numbers )

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].

Solution:

using System;
using System.Collections.Generic;
using System.Text;

namespace LeetCode.Easy
{
 class TwoSumSolution
 {
 public int[] TwoSum(int[] nums, int target)
 {
 var dict = new Dictionary<int, int>();
 var sumSetIndex = new int[2];
 for (int i=0;i<nums.Length;i++)
 { 
 dict.Add(nums[i], i); 
 }

 foreach (var num in nums)
 {
 if (dict.ContainsKey(num))
 { 
 if(dict.ContainsKey(target - num))
 {
 sumSetIndex[0] = dict[num];
 sumSetIndex[1] = dict[target - num]; 
 } 
 }
 }

 return sumSetIndex;
 }
 }
}

Time Complexity: O(n) - For a complete Iteration of N Numbers.

Space Complexity: O(n) - For HashMap

Detail: https://github.com/sumitc91/coding/blob/master/Coding/LeetCode/Easy/TwoSumSolutionDuplicateAllowed.cs