Kth Smallest Element In A BST Problem
Description
LeetCode Problem 230.
Given the root of a binary search tree, and an integer k, return the k^th smallest value (1-indexed) of all the values of the nodes in the tree.
Example 1:
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Input: root = [3,1,4,null,2], k = 1
Output: 1
Example 2:
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Input: root = [5,3,6,2,4,null,null,1], k = 3
Output: 3
Constraints:
- The number of nodes in the tree is n.
- 1 <= k <= n <= 10^4
- 0 <= Node.val <= 10^4
Sample C++ Code
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
vector<int> sorted;
void inorder(TreeNode* node) {
if (node == NULL)
return;
inorder(node->left);
sorted.push_back(node->val);
inorder(node->right);
}
int kthSmallest(TreeNode* root, int k) {
inorder(root);
return sorted[k-1];
}
};