Count Unhappy Friends LeetCode solution in Java

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class Solution {
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  public int unhappyFriends(int n, int[][] preferences, int[][] pairs) {
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    int[][] rankings = new int[n][n]; // smaller the value, higher the preference
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    int[] pairedWith = new int[n];
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    for (int i = 0; i < n; i++) {
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      for (int rank = 0; rank < n - 1; rank++) {
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        int j = preferences[i][rank];
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        rankings[i][j] = rank; // person "i" views person "j" with rank
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      }
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    }
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    int unhappy = 0;
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    for (int[] pair : pairs) {
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      int a = pair[0], b = pair[1];
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      pairedWith[a] = b;
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      pairedWith[b] = a;
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    }
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    for (int a = 0; a < n; a++) {
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      // "a" prefers someone else
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      if (rankings[a][pairedWith[a]] != 0) {
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        for (int b = 0; b < n; b++) {
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          // "b" prefers to be with "a" over their current partner
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          // "a" prefers to be with "b" over their current partner
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          if (b != a
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              && rankings[b][a] < rankings[b][pairedWith[b]]
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              && rankings[a][b] < rankings[a][pairedWith[a]]) {
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            unhappy++;
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            break;
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          }
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        }
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      }
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    }
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    return unhappy;
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  }
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}