/*
 * @lc app=leetcode id=230 lang=java
 *
 * [230] Kth Smallest Element in a BST
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {

    static class State{
        int result;
        int order;
        int targetOrder;
        boolean found;
    }

    public int kthSmallest(TreeNode root, int k) {
        State st = new State();
        st.found = false;
        st.targetOrder = k;
        st.order = 0;
        travel(root, st);
        return st.result;
    }

    private void travel(TreeNode node, State st) {
        if(node == null) {
            return;
        }
        travel(node.left, st);
        st.order++;
        if(st.found) {
            return;
        } else if(st.order == st.targetOrder) {
            st.result = node.val;
            st.found = true;
        } else {
            travel(node.right, st);
        }
    }
}
// @lc code=end