bzoj1491[noi2007]：社交网络(floyd)

传送门：http://www.lydsy.com:808/JudgeOnline/problem.php?id=1491

floyd大水题，不想说什么了。

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
#define INF 0x3f3f3f3f
typedef long long LL;
const int maxn = 110;
int g[maxn][maxn];
LL path[maxn][maxn];
int n, m;
int main() {
    memset(g, 0x3f, sizeof(g));
    scanf("%d%d", &n, &m);
    int u, v, w;
    for(int i = 1; i <= m; i ++) {
        scanf("%d%d%d", &u, &v, &w);
        g[u][v] = w;
        g[v][u] = w;
        path[u][v] = path[v][u] = 1;
    }
    for(int k = 1; k <= n; k ++) {
        for(int i = 1; i <= n; i ++) {
            for(int j = 1; j <= n; j ++) {
                if(i == j || i == k || j == k) continue;
                if(g[i][k] + g[k][j] <= g[i][j]) {
                    if(g[i][k] + g[k][j] < g[i][j]) path[i][j] = 0;
                    g[i][j] = g[i][k] + g[k][j];
                    path[i][j] += path[i][k] * path[k][j];
                }
            }
        }
    }
    for(int k = 1; k <= n; k ++) {
        double ans = 0;
        for(int i = 1; i <= n; i ++) {
            for(int j = 1; j <= n; j ++) {
                if(i == j || i == k || k == j) continue;
                if(g[i][k] + g[k][j] == g[i][j]) ans += (double)(path[i][k] * path[k][j]) / (double)path[i][j];
            }
        }
        printf("%.3lf\n", ans);
    }
    return 0;
}