How to Invert Binary Tree or How to convert a binary tree into its mirror tree.
Given a binary tree, we have to write a code to invert it.
Inverting a binary tree means we have to interchange the left and right children of all non-leaf nodes. In simple words, Output is the mirror of the input tree.
Valid parentheses string with wildcard.
Given a string containing only three types of characters: ‘(‘, ‘)’ and ‘*’. Write a function to check whether this string is valid.
We define the validity of a string by these rules:
1) Any left parenthesis ‘(‘ must have a corresponding right parenthesis ‘)’.
2) Any right parenthesis ‘)’ must have a corresponding left parenthesis ‘(‘.
3) Left parenthesis ‘(‘ must go before the corresponding right parenthesis ‘)’.
4) ‘*’ could be treated as a single right parenthesis ‘)’ or a single left parenthesis ‘(‘ or an empty string.
An empty string is also valid.
For Example –
Example 1:
Input: ” * ( ) ) “, Output: true
In the first example, To balance this string we need to treat star as opening bracket ( “(“).
Example 2:
Input: ” ( * ) “, Output: true
In this example, The start is treated as empty string.
How to check if two nodes are cousins in a Binary tree.
Given two values x and y, we have to write a code to check the nodes corresponding to values x and y are cousins or not. All the values in this binary tree are unique.
Two nodes of a binary tree are cousins if they have the same depth, but have different parents.
In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.