Sorting It All Out

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 26911		Accepted: 9285

Description

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.

Source

AC代码：

#include
     
      #include
      
       #include
       
        #include
        
         #include
         
          #include
          
           using namespace std;int n,m;int in[30],tmp_in[30];int f1,f2;int str[30];vector 
           
             G[30];void top_sort(){ //拓扑排序 f1=0; //没有环 f2=1; //唯一排序 for(int i=0;i
            

s; while(!s.empty()) s.pop(); for(int i=0;i

=2){ f2=0; } int tmp=s.top(); s.pop(); str[counter++]=tmp; for(int i=0;i

>n>>m&&(n!=0||m!=0)){ memset(in,0,sizeof(in)); int i; for(i=0;i

>ch; G[ch[0]-'A'].push_back(ch[2]-'A'); in[ch[2]-'A']++; top_sort(); if(f1){ cout<<"Inconsistency found after "<

<<" relations."<

>ch; break; } else if(f2){ cout<<"Sorted sequence determined after "<

<<" relations: "; for(int j=0;j

>ch; break; } } if(i>=m) cout<<"Sorted sequence cannot be determined."<

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