# [561. Array Partition I](https://leetcode.com/problems/array-partition-i/)
int arrayPairSum(int* nums, int numsSize) {
int i=0,j=numsSize-1;
int sum=0;

void sort(int i,int j,int* nums);
sort(0,numsSize-1, nums);
for(i=0;i<numsSize;i=i+2){
sum+=nums[i];
}

return sum;
}

void sort(int i,int j,int* nums){
int low=i;
int high=j;
int key=nums[i];
int temp=0;

if(i>j){
return ;
}
while(i<j){
while(nums[j]>key&&i<j){
j--;
}
nums[i]=nums[j];
while(nums[i]<=key&&i<j){
i++;

}
nums[j]=nums[i];

}

nums[i]=key;
sort(low,i-1,nums);
sort(i+1,high,nums);

}