1. Take input and print recursive #

Created Saturday 25 January 2020

We want to achieve two things:

1. Print function - void printTree(TreeNode* root)

• Tree has a very easy and intuitive structure, i.e print the root an call print on all the subtrees.
• We don’t require base cases in generic trees, checking for NULL is an edge case. Both are different. Base case nake a recursion stop, while edge cases break the program or cause an error/exception.
• We don’t require a base case coz we never hit a coming back point.
• The caller works as base case.
• We never call from a NULL, coz we are using vectors, so we never use a garbage or empty list.

2. Input function

TreeNode* takeInput() { // ask root data // no. of children // call takeInput three, 3 subtrees done. }

• We create a node, only when we ask the value for it. This we don’t have to keep a track of the variables for the children and all.
• No need of base case as input will be taken if no.of children > 0. Else it will hit brace. i.e we won’t go any further.
• The function creates atleast one node.
• takeInput() is easy to make, but using it is difficult.

We’ll be using recursion in 95% of the tree problems. TreeNode_Input_and_Print.h treeMain.cpp