Postorder Traversal

Easy
0/40
Average time to solve is 15m
Contributed by

Problem statement

You have been given a Binary Tree of 'n' nodes, where the nodes have integer values. Your task is to return its postorder traversal.

For Example:
``````For the given tree below,
Postorder traversal for the given tree will be [4, 5, 2, 3, 1]. Hence, the answer is [4, 5, 2, 3, 1].
``````

Detailed explanation ( Input/output format, Notes, Images )
Sample Input 1:
``````1 2 3 4 -1 -1 5 6 7 -1 -1 -1 -1 -1 -1
``````
Sample Output 1:
``````6 7 4 2 5 3 1
``````
Explanation:
``````The given tree is:
``````

``````Postorder traversal for the given tree will be [6, 7, 4, 2, 5, 3, 1]. Hence, the answer is [6, 7, 4, 2, 5, 3, 1].
``````
Sample Input 2:
``````10 20 11 -1 -1 -1 -1
``````
Sample Output 2:
``````20 11 10
``````
Expected time complexity:
``````The expected time complexity is O(n).
``````
Constraints :
``````1 <= 'n' <= 10^5
0 <= 'data' <= 10^5

where 'n' is the number of nodes and 'data' denotes the node value of the binary tree nodes.

Time limit: 1 sec
``````
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