都不好意思写题解了
跑了4000多ms
纪念下自己A的第二题
(我还有一道freetour II wa20多发没A。。。呜呜呜

#include<bits/stdc++.h>

using namespace std;

#define sz(X) ((int)X.size())

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define index Index

typedef long long ll;

const int N = 5e4+5;

const int INF = 0x3f3f3f3f;

const double pi = acos(-1.0);

int n,k,K;

ll ans;

int ty[N];

struct Node{

    int to,nx;

}E[N<<1];

int head[N], tot, vis[N];

void add(int u,int v) {

    E[tot].to = v; E[tot].nx = head[u]; head[u] = tot++;

}

/***************WeightRoot************/

int all, num, center;

int pp[N], nodes[N];

void findRoot(int x,int pre) {

    nodes[x] = 1; pp[x] = 0;

    for(int i = head[x]; ~i; i = E[i].nx) {

        int y = E[i].to; if(y == pre || vis[y]) continue;

        findRoot(y,x);

        nodes[x] += nodes[y];

        pp[x] = max(pp[x], nodes[y]);

    }

    pp[x] = max(pp[x], all-nodes[x]);

    if(pp[x] < num) {

        num = pp[x]; center = x;

    }

}

int getRoot(int root,int sn) {

    num = INF; all = sn; center = root;

    findRoot(root, -1);

    return center;

}

/****************treecdq**********/

ll has[1050];

ll dp[12][1050];

void getdp(int x, int pre, int num) {

    has[num] ++;

    for(int i = head[x]; ~i; i = E[i].nx) {

        int y = E[i].to; if(y == pre || vis[y]) continue;

        getdp(y,x, num|ty[y]);

    }

}

ll Cal(int x, int chu) {

    ll ret = 0;

    memset(has,0,sizeof(has));

    getdp(x,x,chu|ty[x]);

    for(int i = 0; i <= K; ++i) dp[0][i] = has[i];

    for(int i = 1; i <= k; ++i) {

        for(int j = 0; j <= K; ++j) {

            dp[i][j] = dp[i-1][j];

            if(!(j&(1<<(i-1)))) dp[i][j] += dp[i-1][j^(1<<(i-1))];

        }

    }

    for(int i = 0; i <= K; ++i) ret += has[i]* dp[k][i^K];

    return ret;

}

void work(int x) {

    vis[x] = 1;

    ans += Cal(x,0);

    for(int i = head[x]; ~i; i =  E[i].nx) {

        int y = E[i].to; if(vis[y]) continue;

        ans -= Cal(y,ty[x]);

        work(getRoot(y,nodes[y]));

    }

}

int main(){

    while(~scanf("%d %d",&n,&k)) {

        K = (1<<k)-1;

        memset(vis,0,sizeof(vis));

        memset(head,-1,sizeof(head)); tot = 0;

        for(int i = 1; i <= n; ++i) {

            int a; scanf("%d",&a); a--;

            ty[i] = 1<<a;

        }

        for(int i = 1; i < n; ++i) {

            int a,b; scanf("%d %d",&a,&b);

            add(a, b); add(b, a);

        }

        ans = 0;

        work(getRoot(1,n));

        printf("%lld\n", ans);

    }

    return 0;

}