LeetCode（剑指 Offer）- 54. 二叉搜索树的第k大节点

Posted 2022-05-17 放羊的牧码

题目链接：点击打开链接

题目大意：略

解题思路：略

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• 字节跳动

AC 代码

• Java

/**
 * Definition for a binary tree node.
 * public class TreeNode 
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x)  val = x; 
 * 
 */

class Solution 

    int th;

    List<Integer> list = new ArrayList<>();

    public int kthLargest(TreeNode root, int k) 
        th = k;
        dfs(root);
        return list.get(k - 1);
    

    void dfs(TreeNode node) 

        if (node == null || list.size() == th) 
            return;
        

        dfs(node.right);
        list.add(node.val);
        dfs(node.left);
    

• C++

class Solution 
public:
    int kthLargest(TreeNode* root, int k) 
        this->k = k;
        dfs(root);
        return res;
    
private:
    int res, k;
    void dfs(TreeNode* root) 
        if(root == nullptr) return;
        dfs(root->right);
        if(k == 0) return;
        if(--k == 0) res = root->val;
        dfs(root->left);
    
;