题目链接：https://www.luogu.com.cn/problem/B3611
参考题解：https://www.luogu.com.cn/blog/53022/solution-b3611
floyd
#include <bits/stdc++.h>
using namespace std;
const int maxn = 101;
int n, f[maxn][maxn];
int main() {
scanf("%d", &n);
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
scanf("%d", &f[i][j]);
for (int k = 1; k <= n; k++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
f[i][j] |= f[i][k] & f[k][j];
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (j > 1) putchar(' ');
putchar(f[i][j] ? '1' : '0');
}
puts("");
}
return 0;
}
bitset优化
#include <bits/stdc++.h>
using namespace std;
const int maxn = 101;
int n, a;
bitset<maxn> f[maxn];
int main() {
scanf("%d", &n);
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
scanf("%d", &a), f[i][j] = a;
for (int j = 1; j <= n; j++)
for (int i = 1; i <= n; i++)
if (f[i][j])
f[i] |= f[j];
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (j > 1) putchar(' ');
putchar(f[i][j] ? '1' : '0');
}
puts("");
}
return 0;
}