Convert a Binary Tree into its Mirror Tree

Given a binary tree, invert the binary tree and return it.

Look at the example for more details.

Mirror of a Tree: Mirror of a Binary Tree T is another Binary Tree M(T) with left and right children of all non-leaf nodes interchanged.

Example 1:

Input: 1 / \ 3 2 / \ 4 5 Output: Invert and return 1 / \ 2 3 / \ 5 4

Example 2:

Input: 1 / \ 2 3 / \ / \ 4 5 6 7 Output: Invert and return 1 / \ 3 2 / \ / \ 7 6 5 4

Solution

Do tree traversal through the recursion, and swap the left and right pointers with each other.

Code


public class Solution {
    public TreeNode invertTree(TreeNode root) {
        
        if(root!=null){
            
            TreeNode left=invertTree(root.right);
            TreeNode right=invertTree(root.left);
            
            root.left=left;
            root.right=right;
        }
        
        return root;
    }
}


class TreeNode {
	int val;
	TreeNode left;
	TreeNode right;

	TreeNode(int x) {
		val = x;
		left = null;
		right = null;
	}
}