題目[230. Kth Smallest Element in a BST](230. Kth Smallest Element in a BST)
Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.
Note:
You may assume k is always valid, 1 ≤ k ≤ BST's total elements.
1,利用BST性質(zhì)
思路:中序遍歷是遞增的
public class Solution {
int count = 0;
int result = Integer.MIN_VALUE;
public int kthSmallest(TreeNode root, int k) {
traverse(root, k);
return result;
}
public void traverse(TreeNode root, int k) {
if(root == null) return;
traverse(root.left, k);
count ++;
if(count == k) result = root.val;
traverse(root.right, k);
}
}
