Minimum Swaps to Arrange a Binary Grid LeetCode solution in Java

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class Solution {
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  public int minSwaps(int[][] grid) {
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    int n = grid.length, ans = 0, cur = 0;
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    for (int k = 0; k < n - 1; k++) { // looking for the fitting row for row k
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      for (int i = k; i < n; i++) { // start from row k looking downward
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        for (int j = k + 1; j < n; j++) { // all cell after and at k + 1 must be 0
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          if (grid[i][j] == 1) break;
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          if (j < n - 1) continue;
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          for (int m = i; m > k; m--) { // j == n - 1 here, so we found a valid row
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            int[] tmp = grid[m - 1]; // swap it into the correct row - row k
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            grid[m - 1] = grid[m];
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            grid[m] = tmp;
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            ans++;
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          }
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          i = n;
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        }
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        if (i == n - 1) // i reaches the end and did not find a fitting row, return -1
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        return -1;
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      }
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    }
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    return ans;
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  }
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}