知识点
遇到需要O(1)的解法，要考虑到能不能用上给定数组的空间。
不要一口吃成胖子，慢慢从O(m + n)考虑到O(1)
代码
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| class Solution {
public void setZeroes(int[][] matrix) {
int n = matrix.length;
int m = matrix[0].length;
boolean rowZero = false;
boolean colZero = false;
for (int i = 0; i < n; i++) {
if (matrix[i][0] == 0) {
colZero = true;
break;
}
}
for (int j = 0; j < m; j++) {
if (matrix[0][j] == 0) {
rowZero = true;
break;
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (matrix[i][j] == 0) {
matrix[0][j] = 0;
matrix[i][0] = 0;
}
}
}
for (int i = 1; i < n; i++) {
for (int j = 1; j < m; j++) {
if (matrix[0][j] == 0 || matrix[i][0] == 0) {
matrix[i][j] = 0;
}
}
}
if (rowZero) {
for (int j = 0; j < m; j++) {
matrix[0][j] = 0;
}
}
if (colZero) {
for (int i = 0; i < n; i++) {
matrix[i][0] = 0;
}
}
}
}
|
