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## Postorder Traversal Multiple choice Questions and Answers (MCQs)

Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

In postorder traversal of binary tree right subtree is traversed before visiting root.

True | |

False |

Question 1 Explanation:

Post-order method of traversing involves - i) Traverse left subtree in post-order, ii) Traverse right subtree in post-order, iii) visit the root.

Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

What is the possible number of binary trees that can be created with 3 nodes, giving the sequence N, M, L when traversed in post-order.

15 | |

3 | |

5 | |

8 |

Question 2 Explanation:

5 binary trees are possible and they are,

Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

The post-order traversal of a binary tree is O P Q R S T. Then possible pre-order traversal will be .....

T Q R S O P | |

T O Q R P S | |

T Q O P S R | |

T Q O S P R |

Question 3 Explanation:

The last, second last nodes visited in post-order traversal are root and it's right child respectively. Option T Q R S O P can't be a pre-order traversal, because nodes O, P are visited after the nodes Q, R, S. Option T O Q R P S, can't be valid, because the pre-order sequence given in option T O Q R P S and given post-order traversal creates a tree with node T as root and node O as left subtree. Option T Q O P S R is valid. Option T Q O S P R is not valid as node P is visited after visiting node S.

Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

A binary search tree contains values 7, 8, 13, 26, 35, 40, 70, 75. Which one of the following is a valid post-order sequence of the tree provided the pre-order sequence as 35, 13, 7, 8, 26, 70, 40 and 75?

7, 8, 26, 13, 75, 40, 70, 35 | |

26, 13, 7, 8, 70, 75, 40, 35 | |

7, 8, 13, 26, 35, 40, 70, 75 | |

8, 7, 26, 13, 40, 75, 70, 35 |

Question 4 Explanation:

The binary tree contains values 7, 8, 13, 26, 35, 40, 70, 75. The given pre-order sequence is 35, 13, 7, 8, 26, 70, 40 and 75. So, the binary search tree formed is

Thus post-order sequence for the tree is 8, 7, 26, 13, 40, 75, 70 and 35.

Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

Which of the following pair's traversals on a binary tree can build the tree uniquely?

post-order and pre-order | |

post-order and in-order | |

post-order and level order | |

level order and preorder |

Question 5 Explanation:

A binary tree can uniquely be created by post-order and in-order traversals.

There are 5 questions to complete.