BZOJ 4668: 冷战 并查集&&暴力LCA（雾）

#include<cstdio>
#include<iostream>
#define R register int
const int N=500010;
using namespace std;
inline int g() {
    R ret=0,fix=1; register char ch; while(!isdigit(ch=getchar())) fix=ch==‘-‘?-1:fix;
    do ret=ret*10+(ch^48); while(isdigit(ch=getchar())); return ret*fix;
}
int n,m,tim,lst;
int fa[N],t[N],d[N],rk[N];
int getf(int x) {
    if(x==fa[x]) return x;
    R ret=getf(fa[x]);
    d[x]=d[fa[x]]+1; return ret;
}
inline void merge(int u,int v) { ++tim;
    u=getf(u),v=getf(v);
    if(u==v) return;
    if(rk[u]>=rk[v]) fa[v]=u,t[v]=tim;
    else fa[u]=v,t[u]=tim;
    if(rk[u]==rk[v]) ++rk[u];
}
inline int ask(int u,int v) { R ans=0;
    if(getf(u)!=getf(v)) return 0;
    if(d[u]<d[v]) swap(u,v);
    while(d[u]!=d[v]) ans=max(ans,t[u]),u=fa[u];
    while(u!=v) ans=max(ans,max(t[u],t[v])),u=fa[u],v=fa[v];
    return ans;
}
signed main() {
    n=g(),m=g(); for(R i=1;i<=n;++i) fa[i]=i,rk[i]=1,d[i]=0;
    for(R i=1;i<=m;++i) {
        R k=g(),u=g(),v=g(); u^=lst,v^=lst;
        if(k) printf("%d\n",lst=ask(u,v));
        else merge(u,v);
    }
}