I2F03. Level order traversal of a binary tree P99488


Statement
 

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Your task is to write a program that reads a non empty binary tree of natural numbers, and prints its level order traversal (that is, from top to bottom and from left to right), with a line for each level.

(To see an instance of the tree corresponding to the input-output instance, consult the pdf or ps version of this wording.)

Input

The input consists of the description of non empty a binary tree of natural numbers as it is explained at the exercise : “” of the subject collection.

Output

Your program must print as many lines as levels, with the level order traversal of the tree. Follow the format of the instances.

Public test cases
  • Input

    10
    3 0 7 -1 4 -1 -1 2 -1 -1 5
    4 -1 -1 7 6 -1 1 -1 -1 -1
    

    Output

    level 1: 3
    level 2: 0 5
    level 3: 7 2 4 7
    level 4: 4 6
    level 5: 1
    
  • Input

    1
    7 -1 -1
    

    Output

    level 1: 7
    
  • Input

    4
    9 -1 8 7 -1 6 -1 -1 -1
    

    Output

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