[LeetCode] Problem 226 - Invert Binary Tree

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Invert a binary tree.

Example

Input:

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2
3
4
5
     4
   /   \
  2     7
 / \   / \
1   3 6   9

Output:

1
2
3
4
5
     4
   /   \
  7     2
 / \   / \
9   6 3   1

Code

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public class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}
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public TreeNode invertTree(TreeNode root) {
    if (root == null)
        return null;

    TreeNode temp = invertTree(root.right);
    root.right = invertTree(root.left);
    root.left = temp;

    return root;
}