HDU 1811 Rank of Tetris 拓扑排序+并查集

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <iomanip>
#include <math.h>
#include <map>
using namespace std;
#define FIN     freopen("input.txt","r",stdin);
#define FOUT    freopen("output.txt","w",stdout);
#define INF     0x3f3f3f3f
#define lson    l,m,rt<<1
#define rson    m+1,r,rt<<1|1
typedef long long LL;

const int MAXN=1e5+5;

struct Edge{
   int v,nxt;
}E[MAXN*2];

int Head[MAXN],erear;
int IN[MAXN],P[MAXN],sz;
int Same[MAXN];
int A[MAXN],B[MAXN];
char OP[MAXN];
int Father[MAXN],Rank[MAXN];
int n,m;

void all_init(){
   erear=0;
   memset(Head,-1,sizeof(Head));
   memset(IN,0,sizeof(IN));

   for(int i=0;i<n;i++){
       Father[i]=i;
   }
}

int Find(int x){
    return Father[x]==x?x:(Father[x]=Find(Father[x]));
}


void edge_add(int u,int v){
   E[erear].v=v;
   E[erear].nxt=Head[u];
   Head[u]=erear++;

}


int main()
{
    //FIN
    char op;
    while(~scanf("%d%d",&n,&m))
    {
        int sum=n;
        all_init();
        for(int i=0;i<m;i++){
            scanf("%d %c %d",&A[i],&OP[i],&B[i]);
            if(OP[i]==‘=‘){
                   int root1=Find(A[i]);
                   int root2=Find(B[i]);
                   if(root1!=root2){
                       Father[root2]=root1;
                       sum--;
                   }
            }
        }

        for(int i=0;i<m;i++){
            if(OP[i]==‘=‘){
                continue;
            }
            else if(OP[i]==‘>‘){
                int u=Find(A[i]);
                int v=Find(B[i]);
                edge_add(u,v);
                IN[v]++;
            }
            else if(OP[i]==‘<‘){
                int u=Find(A[i]);
                int v=Find(B[i]);
                edge_add(v,u);
                IN[u]++;
            }

        }

        sz=0;
        queue<int>Q;
        while (!Q.empty()) Q.pop();
        for(int i=0;i<n;i++){
            if(!IN[i]&&Find(i)==i)  Q.push(i);

        }

        bool sign=0;
        while(!Q.empty()){
            if(Q.size()>=2)  sign=1;
            int u=Q.front();
            Q.pop();
            P[sz++]=u;
            sum--;
            for(int i=Head[u];i!=-1;i=E[i].nxt){
                int v=E[i].v;
                IN[v]--;
                if(!IN[v])  Q.push(v);
            }
        }


        /*for(int i=0;i<sz;i++){
            if(i==0)  printf("%d",P[i]);
            else  printf(" %d",P[i]);
        }
        printf("\n");
        cout<<"-----------------sz="<<sz<<endl;
        cout<<sum<<endl;*/
        if(sum>0){
            printf("CONFLICT\n");
        }
        else if(sign){
            printf("UNCERTAIN\n");
        }
        else{
            printf("OK\n");
        }

    }
    return 0;
}