# C++ top-down and bottom-up

• Top-down version of this post.

``````class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
if(matrix.empty()) return;
int m = matrix.size(), n = matrix[0].size(), col0 = 1;
for(int i = 0; i < m; i++){
if(!matrix[i][0]) col0 = 0;
for(int j = 1; j < n; j++)
if(!matrix[i][j]) matrix[0][j] = matrix[i][0] = 0;
}

for(int i = 1; i < m; i++){
for(int j = 1; j < n; j++)
if(!matrix[i][0] || !matrix[0][j]) matrix[i][j] = 0;
if(!col0) matrix[i][0] = 0;
}
for(auto& x: matrix[0]) if(!matrix[0][0]) x = 0;
if(!col0) matrix[0][0] = 0;
}
};
``````

And bottom-up.

``````class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
if(matrix.empty()) return;
int m = matrix.size(), n = matrix[0].size(), col0 = 1;
for(int i = 0; i < m; i++){
if(!matrix[i][0]) col0 = 0;
for(int j = 1; j < n; j++)
if(!matrix[i][j]) matrix[0][j] = matrix[i][0] = 0;
}

for(int i = m - 1; i >= 0; i--){
for(int j = n - 1; j > 0; j--)
if(!matrix[i][0] || !matrix[0][j]) matrix[i][j] = 0;
if(!col0) matrix[i][0] = 0;
}
}
};
``````

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