[BZOJ1782][Usaco2010 Feb]slowdown 慢慢游

#include <cmath>
#include <cstdio>
#include <algorithm>
using namespace std;
char buf[10000000], *ptr = buf - 1;
inline int readint(){
    int f = 1, n = 0;
    char ch = *++ptr;
    while(ch < ‘0‘ || ch > ‘9‘){
        if(ch == ‘-‘) f = -1;
        ch = *++ptr;
    }
    while(ch <= ‘9‘ && ch >= ‘0‘){
        n = (n << 1) + (n << 3) + ch - ‘0‘;
        ch = *++ptr;
    }
    return f * n;
}
const int maxn = 100000 + 10;
struct Edge{
    int to, next;
    Edge(){}
    Edge(int _t, int _n): to(_t), next(_n){} 
}e[maxn * 2];
int fir[maxn] = {0}, cnt = 0;
inline void ins(int u, int v){
    e[++cnt] = Edge(v, fir[u]); fir[u] = cnt;
    e[++cnt] = Edge(u, fir[v]); fir[v] = cnt;
}
int fa[maxn], dep[maxn], siz[maxn], son[maxn];
void dfs1(int u){
    son[u] = 0;
    siz[u] = 1;
    for(int v, i = fir[u]; i; i = e[i].next){
        v = e[i].to;
        if(v == fa[u]) continue;
        fa[v] = u;
        dep[v] = dep[u] + 1;
        dfs1(v);
        siz[u] += siz[v];
        if(!son[u] || siz[v] > siz[son[u]]) son[u] = v;
    }
}
int top[maxn], ref[maxn], tcnt = 0;
void dfs2(int u){
    ref[u] = ++tcnt;
    if(!son[u]) return;
    top[son[u]] = top[u];
    dfs2(son[u]);
    for(int v, i = fir[u]; i; i = e[i].next){
        v = e[i].to;
        if(v == fa[u] || v == son[u]) continue;
        top[v] = v;
        dfs2(v);
    }
}
int n;
#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
int sum[maxn << 2] = {0};
void Update(int qw, int l, int r, int rt){
    sum[rt]++;
    if(l == r) return;
    else{
        int mid = l + r >> 1;
        if(qw <= mid) Update(qw, lson);
        else Update(qw, rson);
    }
}
int Query(int ql, int qr, int l, int r, int rt){
    if(ql <= l && r <= qr) return sum[rt];
    else{
        int mid = l + r >> 1, ret = 0;
        if(ql <= mid) ret += Query(ql, qr, lson);
        if(qr > mid) ret += Query(ql, qr, rson);
        return ret;
    }
}
inline void solve(int x){
    int ans = 0;
    while(top[x] != 1){
        ans += Query(ref[top[x]], ref[x], 1, n, 1);
        x = fa[top[x]];
    }
    ans += Query(ref[1], ref[x], 1, n, 1);
    printf("%d\n", ans);
}
int main(){
    fread(buf, sizeof(char), sizeof(buf), stdin);
    n = readint();
    for(int i = 1; i < n; i++) ins(readint(), readint());
    fa[1] = 0;
    dfs1(1);
    top[1] = 1;
    dfs2(1);
    for(int p, i = 1; i <= n; i++){
        p = readint();
        solve(p);
        Update(ref[p], 1, n, 1);
    }
    return 0;
}