Question
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.
Follow up:
- 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?
Difficulty:Medium
Category:Array
Analyze
Solution
class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
const unsigned int len_r = matrix.size();
const unsigned int len_c = matrix[0].size();
bool done_r[len_r] = {false};
bool done_c[len_c] = {false};
// Check each row
for (int i = 0; i < len_r; ++i) {
for (int j = 0; j < len_c; ++j) {
if (matrix[i][j] == 0) {
done_c[j] = true;
done_r[i] = true;
}
}
}
for (int i = 0; i < len_r; ++i) {
if (done_r[i]) {
for (int j = 0; j < len_c; ++j) {
matrix[i][j] = 0;
}
}
}
for (int i = 0; i < len_c; ++i) {
if (done_c[i]) {
for (int j = 0; j < len_r; ++j) {
matrix[j][i] = 0;
}
}
}
// Check each column
}
};