/**
 * 在BST中插入一个数
 *
 */
public class InsertNumInBST {
    
    

	public static void main(String[] args) {
    
    
		TreeNode root = new TreeNode(5);
		root.left = new TreeNode(2);
		root.right = new TreeNode(6);
		root.left.left = new TreeNode(1);
		root.right.right = new TreeNode(7);
		root.left.right = new TreeNode(4);
		root.left.right.left = new TreeNode(3);
		TreeNode node = insert(root, 20);
		System.out.println(node.val);
	}
	
	static TreeNode insert(TreeNode root,int num) {
    
    
		if (root == null) return new TreeNode(num);
		if (root.val == num) return root;
		if (num < root.val) return insert(root.left, num);
		return insert(root.right, num);
	}

}