厦门大学 ACM 1466 线段树维护

链接 http://acm.xmu.edu.cn/JudgeOnline/problem.php?id=1466

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
inline int max( int a,int b ){return (a)>(b)?(a):(b);}
struct date{
   int pre,pos;
}temp;
struct date2{
    int v,next;
}edge[212345];
struct date3{
    int lt,rt,Max;
}node[4123456];

vector<date>s[112345];
int arr[112345],res[1123456],head[112345],N,M,k;
void add_edge( int u,int v ){
    edge[k].v = v;
    edge[k].next = head[u];
    head[u] = k++;
}
void build_tree( int lt,int rt,int t ){
    node[t].lt = lt; node[t].rt = rt; node[t].Max = 0;
    if( lt == rt ) return ;
    int mid = ( lt + rt )>>1;
    build_tree( lt,mid,t<<1 );
    build_tree( mid+1,rt,t<<1|1 );
}
int update( int pos,int val,int t ){
    if( node[t].lt == node[t].rt ) return node[t].Max = val;
    if( node[t<<1].rt >= pos )  update( pos,val,t<<1 );
    if( node[t<<1|1].lt <= pos )update( pos,val,t<<1|1 );
    return node[t].Max = max( node[t<<1].Max,node[t<<1|1].Max );
}
int query( int lt,int rt,int t ){
    if( node[t].lt == lt && node[t].rt == rt )  return node[t].Max;
    if( node[t<<1].rt >= rt )query( lt,rt,t<<1 );
    else if( node[t<<1|1].lt <= lt )query( lt,rt,t<<1|1 );
         else{
            int a = query( lt,node[t<<1].rt,t<<1 );
            int b = query( node[t<<1|1].lt,rt,t<<1|1 );
            return max( a,b );
         }
}
void DFS( int u,int deep ){
    update( deep,arr[u],1 );
    int len = s[u].size( );
    for( int i = 0; i < len; i++ )
    {
        int pre = deep  - s[u][i].pre;
        if( pre <= 0 )res[s[u][i].pos] = -1;
        else          res[s[u][i].pos] = query( pre,deep,1 );
    }
    for( int i = head[u]; i != -1; i = edge[i].next )
    DFS( edge[i].v,deep+1 );
}
int main( )
{
    while( scanf("%d",&N) != EOF )
    {
        for( int i = 0; i <= N; i++ )s[i].clear( );
        for( int i = 1; i <= N; i++ )
           scanf("%d",&arr[i]);
        int v,k = 0;arr[0] = 0;
        memset( head,-1,sizeof(head) );
        for( int u = 1; u <= N; u++ )
        {
            scanf("%d",&v);
            add_edge( v,u );
        }
          scanf("%d",&M);
        for( int i = 1; i <= M; i++ )
        {
            scanf("%d%d",&temp.pre,&v);
            temp.pos = i;
            s[v].push_back(temp);
        }
        build_tree( 1,N,1 );  DFS( 0,1 );
        for( int i = 1; i <= M; i++ )
        if( res[i] == -1 )printf("Wrong request\n");
        else              printf("%d\n",res[i]);
    }
    return 0;
}