InvertTree.java


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import java.lang.*;
import java.util.*;
import node.*;

class InvertTree {
	public static TreeNode invertTree(TreeNode root) {
		if (root.left == null || root.right == null)
			return root;
		TreeNode tmp = root.right;
		root.right = invertTree(root.left);
		root.left = invertTree(tmp);
		return root;
	}

	public static void main(String[] args) {
		TreeNode leftLeaf = new TreeNode(1);
		TreeNode lMiddleLeaf = new TreeNode(3);
		TreeNode rMiddleLeaf = new TreeNode(6);
		TreeNode rightLeaf = new TreeNode(9);
		TreeNode leftParent = new TreeNode(2, leftLeaf, lMiddleLeaf);
		TreeNode rightParent = new TreeNode(7, rMiddleLeaf, rightLeaf);
		TreeNode root = new TreeNode(4, leftParent, rightParent);
		System.out.println(invertTree(root).val);
	}
}