Topological orderings P62138


Statement
 

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There are n tasks, which have to be done one by one. Some tasks must be done before others: there are m precedence relations between tasks. Write a program that prints all possible ways to order the n tasks according to the m given precedences.

Input

Input consists of a natural number n ≥ 1, followed by a natural number m, followed by m different pairs x, y, indicating that task x must be done before task y. Suppose that the tasks are numbered from 0 to n − 1.

Output

Print, one per line and in lexicographic order, all the ways of sorting the n tasks according to the m given precedences. There will always be at least one solution.

Public test cases
  • Input

    3 1
    1 0
    
    

    Output

    1 0 2
    1 2 0
    2 1 0
    
  • Input

    1 0
    

    Output

    0
    
  • Input

    10 18
    0 3  4 8
    8 3  2 1
    5 7  5 6
    6 8  4 2
    4 0  8 1
    2 8  3 1
    6 2  7 3
    7 2  5 0
    0 6  9 5
    

    Output

    4 9 5 0 6 7 2 8 3 1
    4 9 5 0 7 6 2 8 3 1
    4 9 5 7 0 6 2 8 3 1
    9 4 5 0 6 7 2 8 3 1
    9 4 5 0 7 6 2 8 3 1
    9 4 5 7 0 6 2 8 3 1
    9 5 4 0 6 7 2 8 3 1
    9 5 4 0 7 6 2 8 3 1
    9 5 4 7 0 6 2 8 3 1
    9 5 7 4 0 6 2 8 3 1
    
  • Information
    Author
    Salvador Roura
    Language
    English
    Translator
    Salvador Roura
    Original language
    Catalan
    Other languages
    Catalan
    Official solutions
    C++
    User solutions
    C++