不想再调这道题了。。。这题我早就会了，但是读入实在是坑。。。。就是坑。。。。没错，这次真的是坑。。。。。。
不能在坑题上浪费太多时间，既没有明显提高代码能力，又不能提高思维，也不能学到知识点。
我只能说，出题人心理为何如此阴暗，出这样的题和报复社会有什么区别。。。
#include<iostream> #include<cstdio> #include<cstring> #include<cstdlib> #include<algorithm> #include<vector> #define REP(i,a,b) for(int i=a;i<=b;i++) #define MS0(a) memset(a,0,sizeof(a))using namespace std;typedef long long ll; const int maxn=1000100; const int INF=1e9+10;int n,m; char op[10];int p,q,v; int k,pk[40]; vector<int> d[40];int dn; int fa[maxn],w[maxn],val[maxn]; int flag; int rk; int sz[maxn];void Init() {REP(i,0,2) fa[i]=i,w[i]=0,val[i]=-1,sz[i]=1;REP(i,0,20) d[i].clear(); }int find(int x) {if(fa[x]==x) return x;int t=find(fa[x]);w[t]=0;w[x]^=w[fa[x]];return fa[x]=t; }void Union(int p,int q,int v) {if(flag==0) return;int x=find(p),y=find(q);if(x==y){if((w[p]^w[q])!=v) flag=0;}else{if(sz[x]>sz[y]) swap(x,y),swap(p,q);if(~val[x]&&~val[y]){if((w[p]^val[x]^w[q]^val[y])!=v) flag=0;else{fa[x]=y;sz[y]+=sz[x];sz[x]=0;w[x]=(w[p]^w[q]^v);w[y]=0;}}else{fa[x]=y;w[x]=(w[p]^w[q]^v);w[y]=0;if(val[y]==-1){if(~val[x]) val[y]=(val[x]^w[x]);}}}if(flag==0) printf("The first %d facts are conflicting.\n",rk); }void change(int p,int v) {if(flag==0) return;int x=find(p);if(~val[x]){if((w[p]^val[x])!=v) flag=0;}else val[x]=(v^w[p]);if(flag==0) printf("The first %d facts are conflicting.\n",rk); }bool cmp(int a,int b) {return fa[a]<fa[b]; }int query() {REP(i,1,k) d[i].clear();int res=0;sort(pk+1,pk+k+1,cmp);dn=1;d[1].push_back(pk[1]);int px=fa[pk[1]];REP(i,2,k){if(fa[pk[i]]==px) d[dn].push_back(pk[i]);else{++dn;px=fa[pk[i]];d[dn].push_back(pk[i]);}}REP(i,1,dn){if((int)d[i].size()%2==0){for(int j=0;j<d[i].size();j++) res^=w[d[i][j]];}else{int x=fa[d[i][0]];if(val[x]==-1) return -1;for(int j=0;j<d[i].size();j++) res^=(val[x]^w[d[i][j]]);}}return res; }void solve() {flag=1;rk=0;REP(i,1,m){scanf("%s",op);if(op[0]=='I'){++rk;gets(op);if(sscanf(op,"%d%d%d",&p,&q,&v)==3) Union(p,q,v);else change(p,q);}else{scanf("%d",&k);REP(i,1,k){scanf("%d",&pk[i]);find(pk[i]);}if(flag==0) continue;ll tmp=query();if(tmp==-1) printf("I don't know.\n");else printf("%d\n",tmp);}} }int main() {freopen("in.txt","r",stdin);int casen=1;while(~scanf("%d%d",&n,&m)){if(n==0&&m==0) break;printf("Case %d:\n",casen++);Init();solve();puts("");}return 0; }/** 6 5 I 1 2 1 I 3 4 2 I 4 5 3 Q 2 3 5 Q 4 1 2 3 5 2 6 I 0 1 3 Q 1 0 Q 2 1 0 I 0 2 Q 1 1 Q 1 0 3 3 I 0 1 6 I 0 2 2 Q 2 1 2 2 4 I 0 1 7 Q 2 0 1 I 0 1 8 Q 2 0 1 0 0 */
