package array; import java.util.HashSet; import java.util.Set; /** * Created by pradhang on 3/28/2017. * Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. click to show follow up. Follow up: Did you use extra space? A straight forward solution using O(mn) space is probably a bad idea. A simple improvement uses O(m + n) space, but still not the best solution. Could you devise a constant space solution? */ public class SetMatrixZeroes { /** * Main method * @param args * @throws Exception */ public static void main(String[] args) throws Exception { int[][] matrix = {{0, 8, 7}, {9, 0, 8}, {9, 9, 0}}; new SetMatrixZeroes().setZeroes(matrix); } public void setZeroes(int[][] matrix) { Set row = new HashSet<>(); Set col = new HashSet<>(); int m = matrix.length; int n = matrix[0].length; for(int i = 0; i < m; i ++) { for(int j = 0; j < n; j ++) { if(matrix[i][j] == 0) { row.add(i); col.add(j); } } } for(int r : row) { for(int j = 0; j < n; j++) { matrix[r][j] = 0; } } for(int c : col) { for(int i = 0; i < m; i++) { matrix[i][c] = 0; } } } }