BZOJ4551 [Tjoi2016&Heoi2016]树

来源：互联网发布：做奥数题的软件编辑：程序博客网时间：2024/06/10 01:47

TJOI居然考这么傻逼的题……根JLOI一比真是天壤之别-_-

转成dfs序，然后相当于区间以deep为关键字去max，直接线段树维护就好

#include<iostream>#include<cstdlib>#include<cstdio>#include<cstring>#include<cmath>#include<ctime>#include<algorithm>#include<iomanip>#include<vector>#include<stack>#include<queue>#include<map>#include<set>#include<bitset>using namespace std;#define MAXN 100010#define MAXM 1010#define ll long long#define INF 1000000000#define MOD 1000000007#define eps 1e-8struct vec{int to;int fro;};vec mp[MAXN];int tai[MAXN],cnt;int ch[MAXN*4];int dep[MAXN]; int dfn[MAXN],siz[MAXN],tim;int n,m;inline void be(int x,int y){mp[++cnt].to=y;mp[cnt].fro=tai[x];tai[x]=cnt;}void dfs(int x){int i,y;siz[x]=1;dfn[x]=++tim;for(i=tai[x];i;i=mp[i].fro){y=mp[i].to;if(!siz[y]){dep[y]=dep[x]+1;dfs(y);siz[x]+=siz[y];}}}inline void toch(int x,int y){if(dep[y]>dep[ch[x]]){ch[x]=y;}}inline void pd(int x){if(ch[x]){toch(x<<1,ch[x]);toch(x<<1|1,ch[x]);ch[x]=0;}}void change(int x,int y,int z,int l,int r,int cv){if(y==l&&z==r){toch(x,cv);return ;}pd(x);int mid=y+z>>1;if(r<=mid){change(x<<1,y,mid,l,r,cv);}else if(l>mid){change(x<<1|1,mid+1,z,l,r,cv);}else{change(x<<1,y,mid,l,mid,cv);change(x<<1|1,mid+1,z,mid+1,r,cv);}}int ask(int x,int y,int z,int p){if(y==z){return ch[x];}pd(x);int mid=y+z>>1;if(p<=mid){return ask(x<<1,y,mid,p);}else{return ask(x<<1|1,mid+1,z,p);}}int main(){int i,x,y;char o[2];scanf("%d%d",&n,&m);for(i=1;i<n;i++){scanf("%d%d",&x,&y);be(x,y);}dep[1]=1;dfs(1);change(1,1,n,1,n,1);for(i=1;i<=m;i++){scanf("%s%d",o,&x);if(o[0]=='Q'){printf("%d\n",ask(1,1,n,dfn[x]));}else{change(1,1,n,dfn[x],dfn[x]+siz[x]-1,x);}}return 0;}/*4 41 22 33 4Q 3C 2C 1Q 3*/

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