Count Unhappy Friends LeetCode solution in C++

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class Solution {
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 public:
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  int unhappyFriends(int n, vector<vector<int>> &preferences, vector<vector<int>> &pairs) {
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    int unhappy = 0;
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    int v[n];
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    for (int i = 0; i < n / 2; i++) {
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      v[pairs[i][0]] = pairs[i][1];
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      v[pairs[i][1]] = pairs[i][0];
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    }
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    for (int i = 0; i < n; i++) {
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      int j = 0;
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      int pf = preferences[i][j];
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      while (pf != v[i]) {
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        int z = 0;
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        bool f = false;
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        while (preferences[pf][z] != v[pf]) {
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          if (preferences[pf][z] == i) {
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            unhappy++;
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            f = true;
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            break;
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          }
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          z++;
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        }
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        if (f) break;
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        pf = preferences[i][++j];
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      }
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    }
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    return unhappy;
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  }
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};