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.