剑指offer(六十二)之二叉搜索树的第k个结点

<span style="color:#cc33cc;">/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

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

    }

}
*/
import java.util.Stack;
public class Solution {
    TreeNode KthNode(TreeNode pRoot, int k)
    {
        if(pRoot==null||k==0)
            return null;
        Stack<TreeNode> s=new Stack<TreeNode>();
        s.push(pRoot);
        int count=0;
        TreeNode resNode=null;
        while(!s.isEmpty()){        
            while(!s.isEmpty()&&s.peek()!=null){
                TreeNode temp=s.peek();
                s.push(temp.left);
            }
            s.pop();
            if(!s.isEmpty()&&s.peek()!=null){
                TreeNode node=s.pop();
                count++;
                if(count==k){
                    resNode=node;
                    break;
                }
                s.push(node.right);
            }                       
        }
        return resNode;    
    }
}</span>