hdu 4366（线段树+DFS序）

传送门
问题：给出一棵树，除根结点(0)以外每个点有一个能力值和忠诚度，查询u所在子树结点中找一个能力值比u高并且忠诚度尽量大的点，输出其编号。

按能力值从高到低排序，建出线段树维护区间最大值，跑出dfs序后，先查询，再插入。

#pragma comment(linker,"/STACK:1024000000,1024000000")#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<map>#include<vector>#include<cstdlib>#define lson rt<<1,l,mid#define rson rt<<1|1,mid+1,r#define root 1,1,n-1using namespace std;const int maxn=5e4+2;int n,m;vector<int> G[maxn];map<int,int> mp;struct NODE {    int id,ab,lo;    friend bool operator <(const NODE &a,const NODE &b) {        return a.ab>b.ab||(a.ab==b.ab&&a.id<b.id);    }}ff[maxn];int in[maxn],out[maxn],tim;int maxx[maxn<<2],q[maxn];inline int read() {    int x=0,f=1;char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}    while (c>='0'&&c<='9') x=x*10+c-'0',c=getchar();    return x*f;}inline void pushup(int rt) {    maxx[rt]=max(maxx[rt<<1],maxx[rt<<1|1]);}void build(int rt,int l,int r) {    if (l==r) {        maxx[rt]=-1;        return ;    }    int mid=(l+r)>>1;    build(lson),    build(rson),    pushup(rt);}void modify(int rt,int l,int r,int pos,int val) {    if (l==r) {        maxx[rt]=val;        return ;    }    int mid=(l+r)>>1;    if (pos<=mid) modify(lson,pos,val);    else modify(rson,pos,val);    pushup(rt);}int query(int rt,int l,int r,int L,int R) {    if (L<=l&&r<=R) return maxx[rt];    int mid=(l+r)>>1,ret=-1;    if (L<=mid) ret=max(ret,query(lson,L,R));    if (mid<R) ret=max(ret,query(rson,L,R));    return ret;}void dfs(int p,int f) {    in[p]=tim++;    int siz=G[p].size();    for (int i=0;i<siz;++i) {        int v=G[p][i];        if (v==f) continue;        dfs(v,p);    }    out[p]=tim-1;}int main() {//  freopen("hdu 4366.in","r",stdin);    int kase=read();    while (kase--) {        n=read(),m=read();        for (register int i=0;i<n;++i) G[i].clear();        mp.clear(),mp[-1]=-1,tim=0;        for (register int i=1;i<n;++i) {            int fa=read();            G[fa].push_back(i);            ff[i].lo=read(),ff[i].ab=read(),ff[i].id=i;            mp[ff[i].lo]=i;        }        sort(ff+1,ff+n);        build(root);        dfs(0,0);        for (register int i=1;i<n;++i) {            int tmp=query(root,in[ff[i].id],out[ff[i].id]);            q[ff[i].id]=mp[tmp];            modify(root,in[ff[i].id],ff[i].lo);        }        while (m--) {            int x=read();            printf("%d\n",q[x]);        }    }    return 0;}