forked from kamyu104/LintCode
-
Notifications
You must be signed in to change notification settings - Fork 0
/
maximal-square.cpp
37 lines (35 loc) · 1.09 KB
/
maximal-square.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
// Time: O(m * n)
// Space: O(n)
class Solution {
public:
/**
* @param matrix: a matrix of 0 and 1
* @return: an integer
*/
int maxSquare(vector<vector<int> > &matrix) {
if (matrix.empty()) {
return 0;
}
const int m = matrix.size(), n = matrix[0].size();
vector<vector<int>> size(2, vector<int>(n, 0));
int max_size = 0;
for (int j = 0; j < n; ++j) {
size[0][j] = matrix[0][j];
max_size = max(max_size, size[0][j]);
}
for (int i = 1; i < m; ++i) {
size[i % 2][0] = matrix[i][0];
for (int j = 1; j < n; ++j) {
if (matrix[i][j] == 1) {
size[i % 2][j] = min(size[i % 2][j - 1],
min(size[(i - 1) % 2][j],
size[(i - 1) % 2][j - 1])) + 1;
max_size = max(max_size, size[i % 2][j]);
} else {
size[i % 2][j] = 0;
}
}
}
return max_size * max_size;
}
};