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:
- 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?
my code:
class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
int row = matrix.size();
int col = matrix[0].size();
vector<int> r;
vector<int> c;
for (int i = 0; i < row; ++i) {
for (int j = 0; j < col; ++j) {
if (matrix[i][j] == 0) {
r.push_back(i);
c.push_back(j);
}
}
}
for (int i = 0; i < r.size(); ++i) {
int x = r[i];
int y = c[i];
for (int j = 0; j < col; ++j) {
matrix[x][j] = 0;
}
for (int j = 0; j < row; ++j) {
matrix[j][y] = 0;
}
}
}
};
Runtime: 36 ms, faster than 90.90% of C++ online submissions for Set Matrix Zeroes.