add k smallest in bst

Author: tg123

kth-smallest-element-in-a-bst/README.md

@@ -0,0 +1,51 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+public class Solution {
+
+    boolean reachLeftMost = false;
+    boolean stop = false;
+
+    int kth = 0;
+    int k = 0;
+
+    void search(TreeNode root) {
+
+        if(stop){
+            return;
+        }
+
+        // visit
+        if(root == null){
+            reachLeftMost = true;
+            return;
+        }
+
+        search(root.left);
+
+        if(reachLeftMost) {
+            k--;
+        }
+
+        if(k == 0){
+            kth = root.val;
+            stop = true;
+            return;
+        }
+
+        search(root.right);
+    }
+
+    public int kthSmallest(TreeNode root, int k) {
+        this.k = k;
+        search(root);
+
+        return kth;
+    }
+}

kth-smallest-element-in-a-bst/Solution.java

@@ -0,0 +1,7 @@
+---
+layout: solution
+title: Kth Smallest Element in a BST
+date: 2015-07-02 14:16:21+08:00
+leetcode_id: 230
+---
+{% include_relative README.md %}