/*
* 73. Set Matrix Zeroes
QuestionEditorial Solution My Submissions
Total Accepted: 70785
Total Submissions: 208447
Difficulty: Medium
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
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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?
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*/
package matrix;
import java.util.*;
public class SetZeroes {
public void setZeroes(int[][] matrix) {
// https://discuss.leetcode.com/topic/15193/my-ac-java-o-1-solution-easy-to-read
int m = matrix.length;
int n = matrix[0].length;
boolean fc = false, fr = false;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (matrix[i][j] == 0) {
if (i == 0)
fr = true;
if (j == 0)
fc = true;
matrix[0][j] = 0;
matrix[i][0] = 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 (fr) {
for (int j = 0; j < n; j++) {
matrix[0][j] = 0;
}
}
if (fc) {
for (int i = 0; i < m; i++) {
matrix[i][0] = 0;
}
}
}
public static void main(String[] args) {
int[][] matrix = { { 1, 2, 0, 9, 5 }, { 1, 0, 7, 9, 5 }, { 6, 4, 7, 8, 5 }, { 3, 2, 7, 9, 5 },
{ 4, 1, 7, 9, 0 } };
for (int i = 0; i < matrix.length; i++)
System.out.println(Arrays.toString(matrix[i]));
SetZeroes sz = new SetZeroes();
sz.setZeroes(matrix);
System.out.println("after set zeroes");
for (int i = 0; i < matrix.length; i++)
System.out.println(Arrays.toString(matrix[i]));
/*
* after set zeroes [0, 0, 0, 0, 0] [0, 0, 0, 0, 0] [6, 0, 0, 8, 0] [3,
* 0, 0, 9, 0] [0, 0, 0, 0, 0]
*
*/
}
}