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73. Set Matrix Zeroes
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.
Example 1:
Input: [ [1,1,1], [1,0,1], [1,1,1] ] Output: [ [1,0,1], [0,0,0], [1,0,1] ]
Example 2:
Input: [ [0,1,2,0], [3,4,5,2], [1,3,1,5] ] Output: [ [0,0,0,0], [0,4,5,0], [0,3,1,0] ]
Follow up:
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A straight forward solution using O(m__n) 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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/**
* Runtime: 1 ms, faster than 100.00% of Java online submissions for Set Matrix Zeroes.
*
* Memory Usage: 50.4 MB, less than 5.71% of Java online submissions for Set Matrix Zeroes.
*/
public void setZeroes(int[][] matrix) {
if (Objects.isNull(matrix) || matrix[0].length == 0) {
return;
}
/**
* 0 all is 0;
* 1 row is 0;
* 2 column is 0;
* 3 is not 0;
*/
int flag = 3;
int value = matrix[0][0];
if (value == 0) {
flag = 0;
}
int column = matrix.length;
int row = matrix[0].length;
for (int i = 0; i < column; i++) {
for (int j = 0; j < row; j++) {
if (matrix[i][j] == 0) {
matrix[i][0] = 0;
matrix[0][j] = 0;
if (i == 0 && j > 0 && flag != 0) {
flag = 1;
}
if (i > 0 && j == 0 && flag != 0) {
if (flag == 1) {
flag = 0;
} else {
flag = 2;
}
}
}
}
}
// printMatrix(matrix);
for (int i = 1; i < column; i++) {
if (matrix[i][0] == 0) {
Arrays.fill(matrix[i], 0);
}
}
for (int j = 1; j < row; j++) {
if (matrix[0][j] == 0) {
for (int i = 0; i < column; i++) {
matrix[i][j] = 0;
}
}
}
if (flag == 0) {
Arrays.fill(matrix[0], 0);
for (int i = 0; i < column; i++) {
matrix[i][0] = 0;
}
} else if (flag == 1) {
Arrays.fill(matrix[0], 0);
} else if (flag == 2) {
for (int i = 0; i < column; i++) {
matrix[i][0] = 0;
}
}
}