leetcode

0 class Solution {

1 const static int length = 20001;

2

3 public:

4 int arrayPairSum(vector<int> &nums) {

5 int arr[length] = {0};

6

7 for (int i : nums)

8 arr[i + 10000]++;

9

10 int res = 0;

11 int sub = 0;

12 for (int i = 0; i < length; i++) {

13 if (!arr[i]) continue;

14

15 arr[i] -= sub;

16 res += (arr[i] / 2 + arr[i] % 2) * (i - 10000);

17 sub = arr[i] % 2;

18 }

19 return res;

20 }

21 };