LeetCode Link: https://leetcode.com/problems/two-sum/
Language: C#
Problem Statement
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.
Examples
Example 1:
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Output: 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.
Solution
public class Solution
{
public int[] TwoSum(int[] nums, int target)
{
var dict = new Dictionary<int, int>();
int count = 0;
foreach(var num in nums)
{
dict[num] = count++;
}
for(int i=0; i<nums.Length; i++)
{
var num = nums[i];
var rest = target - num;
if(dict.ContainsKey(rest) && dict[rest] != i)
{
return new[] {i, dict[rest]};
}
}
return null;
}
}