CodeForces 566D 并查集集合合并

#include <stdio.h>
#include <algorithm>
#define MAX 100000
#define LL long long
#define unsigned U
//using namespace std;
int cas=1,T;
int fa[MAX*2+10],next[MAX*2+10],n,q;
void init(int n)
{
    for(int i=1;i<=n;i++) { fa[i]=i;next[i]=i+1; }
}
int find(int x)
{
    return fa[x]==x?x:(fa[x]=find(fa[x]));
}
void merge(int x,int y)
{
    if(x>y) std::swap(x,y);
    for(int i=x+1;i<=y;)
    {
        int xx=find(i);
        int yy=find(i-1);
        fa[xx]=fa[yy]=std::min(xx,yy);
        int tmp=next[i];
        next[i]=next[y];
        i=tmp;
    }
}
int main()
{
    //freopen("1.in","w",stdout);
    //freopen("1.in","r",stdin);
    //freopen("1.out","w",stdout);
    //scanf("%d",&T);
    while(scanf("%d%d",&n,&q)==2)
    {
        init(n);
        int t,x,y;
        while(q--)
        {
            scanf("%d%d%d",&t,&x,&y);
            if(t==3) puts(find(x)==find(y)?"YES":"NO");
            else if(t==2) merge(x,y);
            else
            {
                int xx=find(x);
                int yy=find(y);
                fa[xx]=fa[yy]=std::min(xx,yy);
            }
        }
    }
    //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
    return 0;
}