Closest Binary Search Tree Value -- LeetCode

標籤：

Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target.

Note:

• Given target value is a floating point.
• You are guaranteed to have only one unique value in the BST that is closest to the target.

思路：遞迴求解。因為是二叉搜尋樹，我們不需要遍曆所有的節點，通過prune來提高速度。

 1 /** 2  * Definition for a binary tree node. 3  * struct TreeNode { 4  *     int val; 5  *     TreeNode *left; 6  *     TreeNode *right; 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8  * }; 9  */10 class Solution {11 public:12     int closestValue(TreeNode* root, double target) {13         int res = root->val;14         if (root->left != NULL && (double)res > target) {15             int leftRes = closestValue(root->left, target);16             res = abs(res - target) < abs(leftRes - target) ? res : leftRes;17         }18         if (root->right != NULL && (double)res < target) {19             int rightRes = closestValue(root->right, target);20             res = abs(res - target) < abs(rightRes - target) ? res : rightRes;21         }22         return res;23     }24 };

 

 

Closest Binary Search Tree Value -- LeetCode