classSolution {public:intkthSmallest(TreeNode* root,intk) {returnkthSmallestDFS(root, k); }intkthSmallestDFS(TreeNode* root,int&k) {if(!root)return-1;intval = kthSmallestDFS(root->left, k);if(k ==0)returnval;if(--k ==0)returnroot->val;returnkthSmallestDFS(root->right, k); } ...
What if the BST is modified (insert/delete operations) often and you need to find the kth smallest frequently? How would you optimize the kthSmallest routine? 思路: BST的重要性质:中序遍历(inorder)BST的结果:值从小到大输出所有node 本题k的最小值为1. 解法1: 迭代+栈 解法2: 递归 解法1: ...
*/publicclassSolution{publicintkthSmallest(TreeNoderoot,intk){if(root==null){return-1;}TreeNodecurr=root;while(curr!=null){intleft=count(curr.left);if(left<k-1){k=k-left-1;curr=curr.right;}elseif(left>k-1){curr=curr.left;}else{returncurr.val;}}return-1;}privateintcount(TreeNode...
Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. 求一个二叉搜索树的第k小值。 题目链接:https://leetcode.com/problems/kth-smallest-element-in-a-bst/ 先来看下二叉搜索树的性质,对于任意一个非叶子节点,它的左子树中所有的值必定小于这个节点的val,...
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. Follow up:
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.Follow up: Whatifthe BST is modified (insert/delete operations) often and you need to find the kth smallest frequentl...
230. Kth Smallest Element in a BST Given a binary search tree, write a functionkthSmallestto find thekth smallest element in it. **Note: ** You may assume k is always valid, 1 ≤ k ≤ BST's total elements. Example 1: 代码语言:javascript ...
总体上,我们只需要增加两个变量num和res。num记录中序遍历已经输出的元素个数,当num == k的时候,我们只需要将当前元素保存到res中,然后返回即可。 下边分享下三种遍历方式的解法,供参考。 递归法。 intnum=0;intres;publicintkthSmallest(TreeNoderoot,intk){inorderTraversal(root,k);returnres;}privatevoidin...
https://leetcode.com/problems/kth-smallest-element-in-a-bst/description/ 解题方法: 用中序遍历整个树,因为会优先遍历到最小的节点,然后再--k,看在哪个节点上k == 0,则用全局变量记录这个节点。 Time Complexity: O(N) 完整代码: intkthSmallest(TreeNode*root,intk){intresult=0;boolfind=false;helpe...
Kth Smallest Element in a BST 题目内容 https://leetcode-cn.com/problems/kth-smallest-element-in-a-bst/ 给定一个二叉搜索树,编写一个函数 kthSmallest 来查找其中第 k 个最小的元素。 说明: 你可以假设 k 总是有效的,1 ≤ k ≤ 二叉搜索树元素个数。 题目思路 记住,二叉搜索树可以通过中序遍历...