C语言 | Leetcode C语言题解之第230题二叉搜索树中第K小的元素

题目：

题解：

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*/int search_num(struct TreeNode* root, int k, int *result, int num)
{if(num == k + 1){return k + 1; // 已找到就不往下跑了}if(root->left){num = search_num(root->left, k, result, num);}if(num == k){*result =  root->val;return k + 1; // 已找到就不往下跑了}num++;if(root->right){num = search_num(root->right, k, result, num);}return num;
}int kthSmallest(struct TreeNode* root, int k) {int result = 0;search_num(root, k, &result, 1); // 开始寻找return result;
}