洛谷P3950 部落冲突 [LCT]

　　题目传送门

部落冲突

格式难调，体面就不放了。

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　　分析：

　　julao们应该都看得出来就是个$LCT$板子，战争就$cut$，结束就$link$，询问就$find$。没了。。。

　　太久没打$LCT$，然后发现自己之前貌似理解得并不透彻，打得还是不熟。。。

　　Code：

//It is made by HolseLee on 5th Sep 2018
//Luogu.org P3950
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<iomanip>
#include<algorithm>
using namespace std;

const int N=3e5+;
int n,m,fa[N],ch[N][],sign[N],cnt,q[N],top;
struct War{
    int x,y; bool flag;
}a[N];

inline int read()
{
    char c=getchar(); int num=; bool flag=false;
    while( c<'' || c>'' ) {
        if( c=='-' ) flag=false;
        c=getchar();
    }
    while( c>='' && c<='' ) {
        num=(num<<)+(num<<)+(c^);
        c=getchar();
    }
    return flag ? -num : num;
}

inline void pushdown(int x)
{
    if( !sign[x] ) return;
    int temp=ch[x][];
    sign[ch[x][]=ch[x][]]^=;
    sign[ch[x][]=temp]^=;
    sign[x]=;
}

inline bool isroot(int x)
{
    return (ch[fa[x]][]!=x && ch[fa[x]][]!=x);
}

inline void rotate(int x)
{
    int y=fa[x], z=fa[y];
    int k=ch[y][]==x, w=ch[x][k^];
    if( !isroot(y) ) ch[z][ch[z][]==y]=x;
    ch[x][k^]=y; ch[y][k]=w;
    if( w ) fa[w]=y; fa[x]=z; fa[y]=x;
}

inline void splay(int x)
{
    top=; q[top]=x;
    for(int i=x; !isroot(i); i=fa[i])
        q[++top]=fa[i];
    while( top ) pushdown(q[top--]);
    while( !isroot(x) ) {
        int y=fa[x], z=fa[y];
        if( !isroot(y) ) {
            (ch[y][]==x)^(ch[z][]==y) ? rotate(x) : rotate(y);
        }
        rotate(x);
    }
}

inline void access(int x)
{
    for(int y=; x; y=x,x=fa[x]) {
        splay(x); ch[x][]=y;
    }
}

inline int find(int x)
{
    access(x); splay(x);
    while( ch[x][] )pushdown(x),x=ch[x][];
    splay(x);
    return x;
}

inline void makeroot(int x)
{
    access(x); splay(x); sign[x]^=;
}

inline void split(int x,int y)
{
    makeroot(x); access(y); splay(y);
}

inline void link(int x,int y)
{
    makeroot(x);
    fa[x]=y;
}

inline void cut(int x,int y)
{
    split(x,y);
    fa[x]=ch[y][]=;
}

int main()
{
    n=read(); m=read();
    char opt[]; int x,y;
    for(int i=; i<n; ++i) {
        x=read(), y=read();
        link(x,y);
    }
    for(int i=; i<=m; ++i) {
        scanf("%s",opt);
        if( opt[]=='Q' ) {
            x=read(), y=read();
            if( find(y)==find(x) ) printf("Yes\n");
            else printf("No\n");
        } else if( opt[]=='C' ) {
            x=read(), y=read();
            cut(x,y);
            a[++cnt].x=x, a[cnt].y=y;
            a[cnt].flag=false;
        } else {
            x=read();
            if( a[x].flag ) continue;
            link(a[x].x,a[x].y);
            a[x].flag=true;
        }
    }
    return ;
}