剑指offer面试题63 二叉搜索树的第k个结点

class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}

public class Solution {
	
	

	private int index = 0;

	TreeNode KthNode(TreeNode pRoot, int k) {
		
		if (pRoot != null) {
			TreeNode node = KthNode(pRoot.left, k);
			if (node != null) {
				return node;
			}
			index++;
			if (index == k) {
				return pRoot;
			}
			node = KthNode(pRoot.right, k);
			if (node != null) {
				return node;
			}
			
		}
		return null;
	}


}