OJ-Problems-Source/HDOJ/4900_autoAC.cpp
2016-09-10 11:34:41 +08:00

103 lines
2.8 KiB
C++

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;
const int MAXN = 310;
const int INF = 0x3f3f3f3f;
int mat[MAXN][MAXN], dif[MAXN][MAXN];
int label[MAXN], has[MAXN], tmp[MAXN];
int n, k, T;
int head[MAXN], ecnt;
int to[MAXN << 1], ne[MAXN << 1];
void init() {
memset(head + 1, -1, n * sizeof(int));
ecnt = 0;
}
void add_edge(int u, int v) {
to[ecnt] = v; ne[ecnt] = head[u]; head[u] = ecnt++;
to[ecnt] = u; ne[ecnt] = head[v]; head[v] = ecnt++;
}
int que[MAXN], dis[MAXN];
void bfs(int st) {
memset(dis + 1, 0x3f, n * sizeof(int));
int l = 0, r = 0;
dis[que[r++] = st] = 0;
while(l != r) {
int u = que[l++];
for(int p = head[u]; ~p; p = ne[p]) {
int &v = to[p];
if(dis[u] + 1 < dis[v]) {
dis[v] = dis[u] + 1;
que[r++] = v;
}
}
}
for(int i = 1; i <= n; ++i) mat[st][i] = dis[i];
}
int cnt[MAXN];
void dfs(int u, int f, int& c, int st) {
if(++cnt[has[u]] == 1) c++;
dif[st][u] = c;
for(int p = head[u]; ~p; p = ne[p]) {
int &v = to[p];
if(v == f) continue;
dfs(v, u, c, st);
}
if(--cnt[has[u]] == 0) c--;
}
double per[MAXN];
void initPer(int n = 300) {
per[0] = log(1);
for(int i = 1; i <= n; ++i)
per[i] = per[i - 1] + log(i);
}
double c(int n, int k) {
return per[n] - per[n - k] - per[k];
}
double calc(int a, int b) {
int cnt = 2;
for(int i = 1; i <= n; ++i) {
if(i == a || i == b) continue;
if(mat[i][a] > mat[a][b] || mat[i][b] > mat[a][b]) continue;
if(mat[i][b] == mat[a][b] && i < a) continue;
if(mat[i][a] == mat[a][b] && i < b) continue;
cnt++;
}
if(cnt >= k) return dif[a][b] * exp(c(cnt - 2, k - 2) - c(n, k));
else return 0;
}
double solve() {
if(n < k || k == 0) return 0;
if(k == 1) return 0;
double res = 0;
for(int i = 1; i <= n; ++i) {
for(int j = i + 1; j <= n; ++j) {
res += calc(i, j);
}
}
return res;
}
int main() {
initPer();
scanf("%d", &T);
while(T--) {
scanf("%d%d", &n, &k);
init();
for(int i = 1, a, b; i < n; ++i) {
scanf("%d%d", &a, &b);
add_edge(a, b);
}
for(int i = 1; i <= n; ++i) bfs(i);
for(int i = 1; i <= n; ++i) scanf("%d", &has[i]);
int cnt = 0;
for(int i = 1; i <= n; ++i) tmp[cnt++] = has[i];
sort(tmp, tmp + cnt);
cnt = unique(tmp, tmp + cnt) - tmp;
for(int i = 1; i <= n; ++i) has[i] = lower_bound(tmp, tmp + cnt, has[i]) - tmp;
for(int i = 1, c = 0; i <= n; ++i) dfs(i, 0, c, i);
printf("%.10f\n", solve());
}
}