[BZOJ4668]冷战

并查集按秩合并的裸题。。。

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int N=500005;
int fa[N],lastans,val[N],n,Q,u,v,opt,cnt,dep[N];
bool tong[N];
int find(int x) {
	if(x==fa[x]) return x;
	int f=find(fa[x]);
	dep[x]=dep[fa[x]]+1;
	return f;
}
void merge(int x,int y) {
	++cnt;
	x=find(x),y=find(y);
	if(x==y) return;
	if(dep[x]>dep[y]) swap(x,y);
	fa[x]=y;
	if(dep[x]==dep[y]) dep[y]++;
	val[x]=cnt;
}
int find(int x,int y) {
	int fx=find(x),fy=find(y);
	lastans=0;
	if(fx!=fy) return 0;
	while(x!=y) {
		if(dep[x]<dep[y]) swap(x,y);
		lastans=max(lastans,val[x]);x=fa[x];
	}
	return lastans;
}
int main() {
	scanf("%d%d",&n,&Q);
	for(int i=1;i<=n;i++) fa[i]=i;
	while(Q--) {
		scanf("%d%d%d",&opt,&u,&v);
		switch (opt) {
			case 0:merge(u^lastans,v^lastans);break;
			case 1:printf("%d
",lastans=find(u^lastans,v^lastans));break;
		}
	}
	return 0;
}