HDU 3234 Exclusive-OR 扩展并查集

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int root[20010],val[20010],temp[20],xor[20],roo[20];
int n,Q;

int query(int x){
    int tem;
    if(root[x]!=x){
        tem=root[x];
        root[x] = query(root[x]);    
        val[x]=val[x]^val[tem];
    }
    return root[x];
}

void Union(int x,int y,int Val){
    int tem1,tem2;
    tem1=query(x);
    tem2=query(y);
    if(tem1==n){
       swap(tem1,tem2);
    }
    root[tem1]=tem2;
    val[tem1]=val[x]^val[y]^Val;
}

int main(){
    int l,i,j,k,p,q,v,flag,fa1,fa2,sign,cas,boo,fact;
    int num,in,tem,all,ans;
    char a[10240],str[10240];
    cas=0;
    while(scanf("%d %d",&n,&Q)==2 && !(n==0 && Q==0)){
        fact=0;
        printf("Case %d:\n",++cas);
        for(i=0;i<=n;i++)
            root[i]=i;
        memset(val,0,sizeof(val));
        flag=0;
        for(l=1;l<=Q;l++){
            scanf("%s",a);
            if(flag){gets(str);continue;}
            if(a[0]=='I'){
                fact++;
                gets(str);
                int t=sscanf(str,"%d%d%d",&p,&q,&v);
                if(t==2){
                    swap(q,v);
                    q=n;
                }
                fa1=query(p);
                fa2=query(q);
                if(fa1==fa2){
                    if((val[p]^val[q])!=v)
                         if(!flag){
                            flag=1;
                            printf("The first %d facts are conflicting.\n", fact);
                         }
                }
                else if(fa1!=fa2){
                    Union(p,q,v);
                }
                
            }
            else{
                scanf("%d",&num);
                all=0;
                memset(xor,0,sizeof(xor));
                memset(roo,0,sizeof(roo));
                memset(temp,0,sizeof(temp));
                for(j=1;j<=num;j++){
                    scanf("%d",&in);
                    tem=query(in);
                    if(j!=1){
                        for(k=1;k<=all;k++){
                            if(roo[k]==tem)
                                break;
                        }
                    }
                    if(j==1 || k==all+1){
                        temp[++all]=1;
                        roo[all]=tem;
                        xor[all]=val[in];
                    }
                    else{
                        temp[k]++;
                        xor[k]^=val[in];
                    }
                }
                ans=0;
                if(flag)
                    continue;
                sign=0;
                for(i=1;i<=all;i++){
                    if(temp[i]%2==1 && roo[i]!=n){
                        printf("I don't know.\n");
                        sign=1;
                        break;
                    }
                    ans^=xor[i];
                }
                if(!sign)
                    printf("%d\n",ans);
            }
        }
        puts("");
    }
    return 0;
}