Solution.cpp

class Solution {
public:
    int largestOverlap(vector<vector<int>>& img1, vector<vector<int>>& img2) {
        int n = img1.size();
        map<pair<int, int>, int> cnt;
        int ans = 0;
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (img1[i][j]) {
                    for (int h = 0; h < n; ++h) {
                        for (int k = 0; k < n; ++k) {
                            if (img2[h][k]) {
                                ans = max(ans, ++cnt[{i - h, j - k}]);
                            }
                        }
                    }
                }
            }
        }
        return ans;
    }
};