Lucky Numbers in a Matrix LeetCode solution in Java

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class Solution {
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  public List<Integer> luckyNumbers(int[][] matrix) {
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    List<Integer> luckyNums = new ArrayList();
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    int n = matrix.length;
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    int m = matrix[0].length;
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    for (int[] row : matrix) {
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      int min = row[0];
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      int index = 0;
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      boolean lucky = true;
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      for (int col = 0; col < m; col++) {
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        if (min > row[col]) {
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          min = row[col];
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          index = col;
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        }
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      }
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      for (int r = 0; r < n; r++) {
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        if (min < matrix[r][index]) {
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          lucky = false;
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          break;
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        }
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      }
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      if (lucky) {
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        luckyNums.add(min);
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      }
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    }
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    return luckyNums;
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  }
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}