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Decode the Coding Interview in Java: Real-World Examples

Flip Equivalent Binary Trees

Understand how to determine flip equivalence of binary trees by recursively comparing nodes and their swapped children. Learn base cases, recursive checks, and analyze time and space complexity for an efficient Java solution.

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Description

Let’s start by defining what a flip operation for a binary tree is. We can define it as:

“Choosing any node and swapping the right and left child subtrees.”

A binary tree, T, is flip equivalent to another binary tree, S, if we can make T equal to S after some number of flip operations.

Given the roots of two binary trees, root1 and root2, you have to find out whether the trees are flip equivalent to each other or not. The flipEquiv function should return True if the binary trees are equivalent. Otherwise, it will return False.

Example

Let’s look at the example below:

Coding exercise

Files
main.java
TreeNode.java
Java
class Solution {
    public static boolean flipEquiv(TreeNode root1, TreeNode root2) {
        // write your code here
        return false;
    }
}
Flip equivalent binary tree

Solution

We implement the flipEquiv function using recursion. Like any recursive function, we start by defining the base conditions. We have two base conditions:

  1. If root1 or root2 is null, they are equivalent if and only ...