题目：

An ascending sorted sequence of distinct values is one in which some form of a less-than operator is used to order the elements from smallest to largest. For example, the sorted sequence A, B, C, D implies that A < B, B < C and C < D. in this problem, we will give you a set of relations of the form A < B and ask you to determine whether a sorted order has been specified or not.

Input

Input consists of multiple problem instances. Each instance starts with a line containing two positive integers n and m. the first value indicated the number of objects to sort, where 2 <= n <= 26. The objects to be sorted will be the first n characters of the uppercase alphabet. The second value m indicates the number of relations of the form A < B which will be given in this problem instance. Next will be m lines, each containing one such relation consisting of three characters: an uppercase letter, the character "<" and a second uppercase letter. No letter will be outside the range of the first n letters of the alphabet. Values of n = m = 0 indicate end of input.

Output

For each problem instance, output consists of one line. This line should be one of the following three: 

Sorted sequence determined after xxx relations: yyy...y. 

Sorted sequence cannot be determined. 

Inconsistency found after xxx relations. 

where xxx is the number of relations processed at the time either a sorted sequence is determined or an inconsistency is found, whichever comes first, and yyy...y is the sorted, ascending sequence. 

Sample Input

4 6A
    
     
      
       
        
       
      
     
    

Sample Output

Sorted sequence determined after 4 relations: ABCD.Inconsistency found after 2 relations.Sorted sequence cannot be determined. 题意：输入n,m，n和m为0的时候输入结束，n代表n个字母，接下来输入m组数据，然后让你根据这m组数据判断是否能将这m个字母排序好，要注意在第i组数据能排序好的时候就输出结果，接下来的数据值输入，不进行判断； 分析：这是我第一次做有于拓扑排序有关的题目，根据题意我们需要分为三步：①判断是否形成循环 ②判断是否有序 ③无法判断（题目输入的数据不足以判断） AC代码：

#include
     
      #include
      
       #include
       
        #include
        
         #include
         
          #include
          
           using namespace std;#define N 30char Map[N][N];int indegree[N],p[N];int c;int toposort(int n){ c=0; int sign=1; int temp[N],m,now; for (int i=1;i<=n;i++) temp[i]=indegree[i]; for (int i=1;i<=n;i++) { m=0; for (int j=1;j<=n;j++) if (temp[j]==0) m++,now=j; if (m==0) return 0; //成环 if (m>1) sign=-1; //无法判断 p[c++]=now; temp[now]=-1; for (int j=1;j<=n;j++) if (Map[now][j]==1) temp[j]--; } return sign; //有序}int main(){ int n,m; char w[5]; int x,y; while (scanf("%d%d",&n,&m)&&(n!=0||m!=0)) { int flag=0; memset(Map,0,sizeof(Map)); memset(indegree,0,sizeof(indegree)); for (int i=1;i<=m;i++) { scanf("%s",w); if (flag) continue; x=w[0]-'A'+1; y=w[2]-'A'+1; Map[x][y]=1; //x->y indegree[y]++; //后者入度+1 int t=toposort(n); if (t==0) printf("Inconsistency found after %d relations.\n",i),flag=1; else if (t==1) { printf("Sorted sequence determined after %d relations: ",i); for(int j=0;j