Data Structure - Mark Entire Row and Column Zero if an Element of an MxN Matrix is Zero

When you're asked to mark an entire row and an entire column with 0's if an element of an MxN matrix is 0, here's my thought process:

1. Define the contract of the function.
   
2. Code the 2-passes algorithm.

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The code below implements the solution:

public static void setZeros(int[][] matrix) {
  int[] row = new int[matrix.length];
  int[] column = new int[matrix[0].length];

  // Store the row and column index with value 0 
  for (int i = 0; i < matrix.length; i++) {
    for (int j = 0; j < matrix[0].length;j++) {
      if (matrix[i][j] == 0) {
        row[i] = 1;
        column[j] = 1;
      }
    } 
  }

  // Set arr[i][j] to 0 if either row i or column j has a 0 
  for (int i = 0; i < matrix.length; i++) {
    for (int j = 0; j < matrix[0].length; j++) {
      if ((row[i] == 1 || column[j] == 1)) { 
        matrix[i][j] = 0;
      }
    }
  }
} 

#1) Define the contract of the function

Name the function setZeros() to operate on a passed-in a 2-dimension int array, which will set all rows and columns of the matrix to zero if the element is 0.

  public static void setZeros(int[][] matrix)

#2) Generic case algorithm

Use a 2-passes scanning approach.

The first pass scans through the entire int[][] matrix to see which row and column has 0. During the scan, on detecting element being 0, flag the corresponding rows/columns to indicate they have 0's. For storing the flags, introduce a int[] for flagging rows and another int[] for flagging columns.

int[] row = new int[matrix.length];
int[] column = new int[matrix[0].length];

The second pass scans through the entire int[][] matrix again to set the element to 0 if the corresponding row flag or column flag indicate the element should be set to 0.

The key concepts here are that int[][] is used to store the matrix, and utilizes a row array (int[]) and a column array (int[]) to store flags.