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| #include <iostream>
#include <algorithm>
using namespace std;
const int N = 2010;
int n, k;
char g[N][N];
int b[N][N];
void insert(int x1, int y1, int x2, int y2) {
b[x1][y1] ++;
b[x2 + 1][y1]--;
b[x1][y2 + 1]--;
b[x2 + 1][y2 + 1]++;
}
int main() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++)
cin >> g[i][j];
}
for (int i = 1; i <= n; i++) {
int l, r;
l = N, r = 0;
for (int j = 1; j <= n; j++) {
if (g[i][j] == 'B') {
l = min(l, j);
r = max(r, j);
}
}
if (l > r) {
insert(1, 1, n - k + 1, n - k + 1);
} else if (r - l + 1 <= k) {
insert(max(1, i - k + 1), max(1, r - k + 1), min(i, n - k + 1), min(l, n - k + 1));
}
}
for (int i = 1; i <= n; i++) {
int up, down;
up = N, down = 0;
for (int j = 1; j <= n; j++) {
if (g[j][i] == 'B') {
up = min(up, j);
down = max(down, j);
}
}
if (up > down) {
insert(1, 1, n - k + 1, n - k + 1);
} else if (down - up + 1 <= k) {
insert(max(1, down - k + 1), max(1, i - k + 1), min(up, n - k + 1), min(i, n - k + 1));
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++)
b[i][j] += b[i][j - 1] + b[i - 1][j] - b[i - 1][j - 1];
}
int res = 0;
for (int i = 1; i <= n - k + 1; i++) {
for (int j = 1; j <= n - k + 1; j++)
res = max(res, b[i][j]);
}
cout << res << endl;
return 0;
}
|
