BZOJ2588: Spoj 10628. Count on a tree

传送门

刚开始看错题以为是dfs序瞎搞..

后来看清题了开始想用树剖瞎搞...

感觉要滚粗啊..

对于每个点到根的路径建立线段树，暴力建MLE没跑，上主席树，然后$(x,y)$的路径就可以先求出来$LCA$,然后就可以用$T_x+T_y-T_{LCA}-T_{fa[LCA]}$就行了。

//BZOJ 2588
//by Cydiater
//2016.12.8
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <iomanip>
#include <cstring>
#include <string>
#include <algorithm>
#include <queue>
#include <map>
#include <ctime>
#include <bitset>
#include <set>
#include <vector>
using namespace std;
#define ll long long
#define up(i,j,n)		for(int i=j;i<=n;i++)
#define down(i,j,n)		for(int i=j;i>=n;i--)
#define cmax(a,b)		a=max(a,b)
#define cmin(a,b)		a=min(a,b)
#define Auto(i,node)		for(int i=LINK[node];i;i=e[i].next)
const int MAXN=1e5+5;
const int oo=0x3f3f3f3f;
inline int read(){
	char ch=getchar();ll x=0,f=1;
	while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}
int N,M,dfn[MAXN],dfs_clock=0,fsort[MAXN],val[MAXN],root[MAXN],rnum=0,cnt=0,fa[MAXN][25],ans=0;
struct Graph{
	int LINK[MAXN],len,dep[MAXN];
	struct edge{
		int y,next;
	}e[MAXN<<1];
	inline void insert(int x,int y){e[++len].next=LINK[x];LINK[x]=len;e[len].y=y;}
	inline void Insert(int x,int y){insert(x,y);insert(y,x);}
	void make_graph(){
		N=read();M=read();
		up(i,1,N)val[i]=fsort[i]=read();
		sort(fsort+1,fsort+N+1);
		rnum=unique(fsort+1,fsort+N+1)-(fsort+1);
		up(i,1,N)val[i]=lower_bound(fsort+1,fsort+rnum+1,val[i])-fsort;
		up(i,1,N-1){
			int x=read(),y=read();
			Insert(x,y);
		}
	}
	void dfs(int node,int deep,int father){
		dfn[++dfs_clock]=node;
		dep[node]=deep;fa[node][0]=father;
		Auto(i,node)if(e[i].y!=father)
			dfs(e[i].y,deep+1,node);
	}
	void set_anc(){
		up(i,1,20)up(node,1,N)
			if(fa[node][i-1])fa[node][i]=fa[fa[node][i-1]][i-1];
	}
	int LCA(int x,int y){
		if(x==y)		return x;
		if(dep[x]<dep[y])	swap(x,y);
		down(i,20,0)if(dep[x]-(1<<i)>=dep[y])x=fa[x][i];
		if(x==y)		return x;
		down(i,20,0)if(fa[x][i]!=0&&fa[x][i]!=fa[y][i]){
			x=fa[x][i];
			y=fa[y][i];
		}
		return fa[x][0];
	}
}G;
struct Chair_man_Tree{
	int son[2],sum;
}t[MAXN<<5];
namespace solution{
	int NewNode(int sum,int son0,int son1){
		t[++cnt].sum=sum;t[cnt].son[0]=son0;t[cnt].son[1]=son1;
		return cnt;
	}
	void insert(int leftt,int rightt,int &Root,int last,int pos){
		Root=NewNode(t[last].sum+1,t[last].son[0],t[last].son[1]);
		int mid=(leftt+rightt)>>1;
		if(leftt==rightt)	return;
		if(pos<=mid)		insert(leftt,mid,t[Root].son[0],t[last].son[0],pos);
		else			insert(mid+1,rightt,t[Root].son[1],t[last].son[1],pos);
	}
	void Prepare(){
		G.make_graph();
		G.dfs(1,0,0);
		G.set_anc();
		up(i,1,N){
			int node=dfn[i],father=fa[node][0],pos=val[node];
			insert(1,rnum,root[node],root[father],pos);
		}
	}
	int Get(int leftt,int rightt,int rx,int ry,int rlca,int rflca,int rnk){
		int sum=t[t[rx].son[0]].sum+t[t[ry].son[0]].sum-t[t[rlca].son[0]].sum-t[t[rflca].son[0]].sum;
		if(leftt==rightt)	return fsort[leftt];
		int mid=(leftt+rightt)>>1;
		if(rnk<=sum)	return Get(leftt,mid,t[rx].son[0],t[ry].son[0],t[rlca].son[0],t[rflca].son[0],rnk);
		else		return Get(mid+1,rightt,t[rx].son[1],t[ry].son[1],t[rlca].son[1],t[rflca].son[1],rnk-sum);
	}
	void Slove(){
		while(M--){
			int x=read()^ans,y=read(),k=read(),lca=G.LCA(x,y);
			printf("%d",ans=Get(1,rnum,root[x],root[y],root[lca],root[fa[lca][0]],k));
			if(M)puts("");
		}
	}
}
int main(){
	//freopen("input.in","r",stdin);
	using namespace solution;
	Prepare();
	Slove();
	return 0;
}