Title
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]
]
Solution
//cpp:
class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
int n = matrix.size();
int m = matrix[0].size();
vector<int> r(n), c(m);
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (matrix[i][j] == 0) {
r[i] = 1;
c[j] = 1;
}
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (r[i] || c[j]) {
matrix[i][j] = 0;
}
}
}
}
};
void setZeroes(vector<vector<int> > &matrix) {
int col0 = 1, rows = matrix.size(), cols = matrix[0].size();
for (int i = 0; i < rows; i++) {
if (matrix[i][0] == 0) col0 = 0;
for (int j = 1; j < cols; j++)
if (matrix[i][j] == 0)
matrix[i][0] = matrix[0][j] = 0;
}
for (int i = rows - 1; i >= 0; i--) {
for (int j = cols - 1; j >= 1; j--)
if (matrix[i][0] == 0 || matrix[0][j] == 0)
matrix[i][j] = 0;
if (col0 == 0) matrix[i][0] = 0;
}
}