poj1094 恶心题，，每次加边进行判断

/*
给定一组偏序关系，问最少第几步能确定次序
如果出现环，问第几步出现环
因为要求第几步确定次序或者第几步出现环，所以每次读入一个偏序关系就进行一次拓扑排序
*/
#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
const int N = ;
int in[N]; //入度
bool Map[N][N]; //临接矩阵此题可以随便用
char out[N]; //拓扑排序输出数组

int topsort( int n ) {
    priority_queue<int,vector<int>,greater<int> > q;  //优先队列忠实粉丝
    int flag = ,k;
    int zeroflag = ;
    int num = ,temp[N];
    memcpy(temp,in,sizeof(in));//拷贝
    for( int i = ; i < n; i++ ) {
        if( !in[i] ) q.push(i);
    }
    while( !q.empty() ) {
        if( q.size() >  )
            zeroflag = ;//要注意在while里面判断 因为此过程中也可能出现入度0不止一个的情况
        k = q.top();
        q.pop();
        num++;
        out[num] = k + 'A'; //num计数 以存到out里面
        for(int i = ; i < n; i++ )
            if(Map[k][i]== && --temp[i] == )
                q.push(i);
    }
    if( num != n ) return ;
    if( zeroflag ==  ) return ;//多个点入度为零
    return -;
}
int main(){
    int n,m,k;
    int step; //记录操作数
    int circleflag,orderflag;
    char s[];
    while( scanf("%d%d", &n, &m) != EOF && n ){
        circleflag=;orderflag=;
        memset(Map,,sizeof(Map));
        memset(in,,sizeof(in));
        for( int i = ; i <= m; i++ ){
            scanf("%s", s);
            if( circleflag ==  && orderflag ==  ){ //已经判出了 就不读了
                if(Map[s[]-'A'][s[]-'A'] == ){
                    circleflag=; //有环了
                    printf("Inconsistency found after %d relations.\n", i);
                    continue ;
                }
                if(Map[s[]-'A'][s[]-'A'] == ){
                    Map[s[]-'A'][s[]-'A'] = ;
                    in[s[]-'A']++;
                }
                k = topsort(n);
                if( k ==  ){
                    circleflag=;
                    printf("Inconsistency found after %d relations.\n", i);
                }
                else if( k == - ){
                    orderflag=;
                    step=i; //记录位置
                }
            }
        }
        if(circleflag ==  && orderflag == )
            printf("Sorted sequence cannot be determined.\n");
        else if(orderflag == ){
            printf("Sorted sequence determined after %d relations: ", step);
            for(int i=; i<=n; i++)
                printf("%c", out[i]);
            printf(".\n");
        }
    }
    return ;
}