leetcode

0 class FindSumPairs {

1 unordered_map<int, int> count1, count2;

2 vector<int> arr;

3

4 public:

5 FindSumPairs(const vector<int> &nums1, const vector<int> &nums2) : arr(nums2) {

6 for (const int n : nums1)

7 count1[n]++;

8 for (const int n : nums2)

9 count2[n]++;

10 }

11

12 void add(int index, int val) {

13 count2[arr[index]]--;

14 arr[index] += val;

15 count2[arr[index]]++;

16 }

17

18 int count(int tot) const {

19 int res = 0;

20

21 for (const auto [k, v] : count1) {

22 const auto it = count2.find(tot - k);

23 if (!v || it == count2.end()) continue;

24 res += v * it->second;

25 }

26

27 return res;

28 }

29 };