1583. 统计不开心的朋友 2021-08-14

class Solution {
private:
    bool x_is_unhappy_for_u(int x, int y, int u, int v, vector<vector<int> > &love_score) {
        if (love_score[x][u] > love_score[x][y] && love_score[u][x] > love_score[u][v])
            return true;
        return false;
    }
public:
    int unhappyFriends(int n, vector<vector<int>> &preferences, vector<vector<int>> &pairs) {
        vector<vector<int> > love_score(n, vector<int>(n));
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n - 1; ++j) {
                love_score[i][preferences[i][j]] = n - j;
            }
        }
        int count = 0;
        vector<bool> un_happy(n, false);
        for (int i = 0; i < n / 2; ++i) {
            for (int j = i + 1; j < n / 2; ++j) {
                int x = pairs[i][0];
                int y = pairs[i][1];
                int u = pairs[j][0];
                int v = pairs[j][1];
                if (x_is_unhappy_for_u(x, y, u, v, love_score) ||
                        x_is_unhappy_for_u(x, y, v, u, love_score))
                    un_happy[x] = true;
                if (x_is_unhappy_for_u(y, x, u, v, love_score) ||
                        x_is_unhappy_for_u(y, x, v, u, love_score))
                    un_happy[y] = true;
                if (x_is_unhappy_for_u(u, v, x, y, love_score) ||
                        x_is_unhappy_for_u(u, v, y, x, love_score))
                    un_happy[u] = true;
                if (x_is_unhappy_for_u(v, u, x, y, love_score) ||
                        x_is_unhappy_for_u(v, u, y, x, love_score))
                    un_happy[v] = true;
            }
        }
        for (bool i : un_happy)
            if (i) ++count;
        return count;
    }
};

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