# Leet code | Problem 1: Two-sum

NOTE: This problem is generated by LeetCode. TakeTheNotes has given only solution for educational purpose.

Problem Name: Two Sum

Description: 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 + nums == 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:

```int* twoSum(int* nums, int numsSize, int target, int* returnSize){

int *retVal = NULL;

if(returnSize == NULL)
{
returnSize = calloc(1, sizeof(int));
if(returnSize == NULL)
{
return NULL;
}
}
*returnSize = 0;

for(int x = 0; x < numsSize; x++)
{
for(int y = x+1; y < numsSize; y++)
{
if( nums[x] + nums[y] == target)
{
retVal = calloc(2, sizeof(int));

if(retVal == NULL)
{
//As we are not able to alloc memory so returning
return NULL;
}

retVal = x;
retVal = y;

*returnSize = 2;
return retVal;
}
}
}

return retVal;
}
```