UVALive 4487 异或并查集

位运算很强大啊

这个题解中文讲解很详细，个人感觉代码上稍微有点繁琐，但总体很容易看懂

其他几个题解，代码看一眼，先来十几个define，，，GG

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const int N=23333,T=N-10;
int n,Q,op,p,q,va,k,ans,cas=1;
int home[N],v[N],a[20],vis[N];
bool ok;

int FIND(int x){
    if (home[x]==x)return x;
    int kk=home[x];
    home[x]=FIND(home[x]);
    v[x]^=v[kk];
    return home[x];
}

bool check(int i,int j,int va){
    int r1=FIND(i),r2=FIND(j);
    if (r1==r2)return (v[i]^v[j])==va;
    if (r1==T ) swap(r1,r2);
    home[r1] = r2;
    v[r1]=v[i]^v[j]^va;
    return 1;
}

int main(){
    //freopen("fuck.in","r",stdin);
    for (;scanf("%d%d",&n,&Q)==2;cas++){
        if (n==0&&Q==0)break;
        printf("Case %d:\n",cas);
        for (int i=0;i<=n+1;i++)home[i]=i;
        memset(v,0,sizeof(v));
        home[T]=T;
        ok=1; op=0;
        for (int time=0;time<Q;time++){
            char ch[2]; scanf("%s",ch);
            if (ch[0]=='I') {
                char st[55]; gets(st); op++;
                if (sscanf(st,"%d%d%d",&p,&q,&va)==2) 
                    { va = q ; q = T ; }
                if (!ok)continue;
                if (!check(p,q,va)){
                    ok=0;
                    printf("The first %d facts are conflicting.\n",op);
                }
            }
            else {
                ans=0;  scanf("%d",&k);
                memset(vis,0,sizeof(vis));
                for (int i=0;i<k;i++){
                    scanf("%d",&a[i]);
                    if (!ok)continue;
                    int root=FIND(a[i]);
                    ans^=v[a[i]];
                    a[i]=root;
                    vis[root]^=1;
                }
                if (!ok)continue;
                bool okk=1;
                for (int i=0;i<k;i++)
                    if (vis[a[i]]&&a[i]!=T)okk=0;
                if (okk)printf("%d\n",ans);
                else puts("I don't know.");
            }
        }
        puts("");
    }
    return 0;
}