LeetCode Q270: Closest Binary Search Tree Value

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.

Solution:

	/**
	* Definition for a binary tree node.
	* struct TreeNode {
	* int val;
	* TreeNode *left;
	* TreeNode *right;
	* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
	* };
	*/
	class Solution {
	public:
	void helper(TreeNode* root, double target, double& closestV){
	if(root==NULL)
	return;
	closestV=fabs(target-root->val)<=fabs(closestV-target)? root->val:closestV;
	if(target>root->val)
	helper(root->right, target, closestV);
	if(target<root->val)
	helper(root->left, target, closestV);
	}
	int closestValue(TreeNode* root, double target) {
	if(root==NULL)
	return 0;
	double closestV=double(INT_MAX)*10;
	helper(root, target, closestV);
	return int(closestV);
	}
	};

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