bzoj 5072

#include <bits/stdc++.h>

const int N = 5010;

#define gc getchar()

inline int read() {
    int x = 0; char c = gc;
    while(c < ‘0‘ || c > ‘9‘) c = gc;
    while(c >= ‘0‘ && c <= ‘9‘) x = x * 10 + c - ‘0‘, c = gc;
    return x;
}

int head[N], cnt;
struct Node {
    int u, v, nxt;
} G[N << 1];
int n, q;
int v[N];
int f[N][N], g[N][N];
int size[N];

inline void Add(int u, int v) {G[++ cnt].v = v; G[cnt].nxt = head[u]; head[u] = cnt;}

void Dfs(int x, int fa) {
    size[x] = 1, f[x][1] = g[x][1] = v[x];
    for(int i = head[x]; ~ i; i = G[i].nxt) {
        int v = G[i].v;
        if(v != fa) {
            Dfs(v, x);
            for(int j = size[x]; j >= 1; j --) {
                for(int k = size[v]; k >= 1; k --) {
                    f[x][j + k] = std:: min(f[x][j + k], f[x][j] + f[v][k]);
                    g[x][j + k] = std:: max(g[x][j + k], g[x][j] + g[v][k]);
                }
            }
            size[x] += size[v];
        }
    }
    for(int i = 1; i <= n; i ++) {
        f[0][i] = std:: min(f[0][i], f[x][i]);
        g[0][i] = std:: max(g[0][i], g[x][i]);
    }
}

int main() {
    int t = read();
    for(; t; t --) {
        cnt = 0;
        memset(f, 0x3f, sizeof f);
        memset(g, 0xc0, sizeof g);
        n = read(); q = read();
        for(int i = 1; i <= n; i ++) head[i] = -1;
        for(int i = 1; i < n; i ++) {
            int u = read(), v = read();
            Add(u, v), Add(v, u);
        }
        for(int i = 1; i <= n; i ++) v[i] = read();
        Dfs(1, 0);
        for(; q; q --) {
            int x = read(), y = read();
            if(f[0][x] <= y && y <= g[0][x]) puts("YES");
            else puts("NO");
        }
        puts("");
    }
    return 0;
}