Invert Binary Tree

Invert a binary tree.

Example:

Input:

     4
   /   \
  2     7
 / \   / \
1   3 6   9

Output:

     4
   /   \
  7     2
 / \   / \
9   6 3   1

Ans:

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

Invert Binary Tree

Invert a binary tree.

     4
   /   \
  2     7
 / \   / \
1   3 6   9

to

     4
   /   \
  7     2
 / \   / \
9   6 3   1

Solution:

public TreeNode invertTree(TreeNode root) {
        
        if (root == null) {
            return null;
        }

        final TreeNode left = root.left,
                right = root.right;
        root.left = invertTree(right);
        root.right = invertTree(left);
        return root;
    }