Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
Have you met this question in a real interview?
Yes
Example
Given a matrix
[
[1,2],
[0,3]
],
return [ [0,2], [0,0] ]
Challenge
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 Solution {
/**
* @param matrix: A list of lists of integers
* @return: Void
*/
public void setZeroes(int[][] matrix) {
// write your code here
if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
boolean firstRowZero = false, firstColZero = false;
int m = matrix.length, n = matrix[0].length;
for(int i = 0; i < m; i++){
if(matrix[i][0] == 0){
firstColZero = true;
break;
}
}
for(int i = 0; i < n; i++){
if(matrix[0][i] == 0){
firstRowZero = true;
break;
}
}
for(int i = 1; i < m; i++){
for(int j = 1; j < n; j++){
if(matrix[i][j] == 0){
matrix[i][0] = 0;
matrix[0][j] = 0;
}
}
}
for(int i = 1; i < m; i++){
for(int j = 1; j < n; j++){
if(matrix[i][0] == 0 || matrix[0][j] == 0){
matrix[i][j] = 0;
}
}
}
if(firstColZero){
for(int i = 0; i < m; i++){
matrix[i][0] = 0;
}
}
if(firstRowZero){
for(int i = 0; i < n; i++){
matrix[0][i] = 0;
}
}
}
}
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