【hdu4366】dfs序线段树

#include <bits/stdc++.h>
#define ll long long
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
using namespace std;
const int N = 5e4+5;

vector<int> ve[N];
int b[N], c[N], tot;
int l[N], r[N], ans[N];
void dfs(int fa, int x){
    tot++;
    l[x] = tot;
    for(int i = 0; i < ve[x].size(); i++){
        int y = ve[x][i];
        if(y == fa) continue ;
        dfs(x, y);
    }
    r[x] = tot;
}

struct Node{
    int b, pos;
    Node(){}
    Node(int b, int pos): b(b), pos(pos){}
    bool operator <(const Node& a) const{
        return b < a.b;
    }
};
Node T[N<<2];

void pushup(int rt){
    T[rt] = max(T[rt<<1], T[rt<<1|1]);
}
void build(int l, int r, int rt){
    T[rt].b = T[rt].pos = -1;
    if(l == r) return ;
    int m = l+r >> 1;
    build(lson);
    build(rson);
}
void update(int pos, Node x, int l, int r, int rt){
    if(pos == l&&r == pos){
        T[rt] = x;
        return ;
    }
    int m = l+r >> 1;
    if(pos <= m) update(pos, x, lson);
    else update(pos, x, rson);
    pushup(rt);
}
Node query(int L, int R, int l, int r, int rt){
    if(L <= l&&r <= R)
        return T[rt];
    int m = l+r >> 1;
    Node ret = Node(-1, -1);
    if(L <= m) ret = max(ret, query(L, R, lson));
    if(R > m) ret = max(ret, query(L, R, rson));
    return ret;
}

struct p{
    int b, c, id, kth;
    p(){}
    p(int b, int c, int id, int kth):b(b), c(c), id(id), kth(kth){}
    bool operator < (const p& a) const{
        return c != a.c? c > a.c: kth < a.kth;
    }
};
p pp[N];

int main(){
    int t; scanf("%d", &t);
    while(t--){
        int n, m, x;
        scanf("%d%d", &n, &m);
        for(int i = 0; i < n; i++) ve[i].clear();
        b[0] = c[0] = -1;
        for(int i = 1; i < n; i++){
            scanf("%d%d%d", &x, b+i, c+i);
            ve[x].push_back(i);
        }

        tot = 0;
        dfs(-1, 0);
        for(int i = 0; i < n; i++)
            pp[i] = p(b[i], c[i], i, l[i]);
        sort(pp+1, pp+n);
        build(1, n, 1);
        for(int i = 1; i < n; i++){
            int j = pp[i].id;
            int L = l[j]+1, R = r[j];
            if(L > R) ans[j] = -1;
            else
                ans[j] = query(L, R, 1, tot, 1).pos;
            update(l[j], Node(pp[i].b, pp[i].id), 1, tot, 1);
        }
        while(m--){
            scanf("%d", &x);
            printf("%d
", ans[x]);
        }
    }
    return 0;
}