leetcode 270: Closest Binary Search Tree Value

Closest Binary Search Tree Value

Total Accepted: 1815 Total Submissions: 6418 Difficulty: Easy

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]

closest必然在查找路径上.

[CODE]

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int closestValue(TreeNode root, double target) {
        
        int closest = root.val;
        double min = Double.MAX_VALUE;
        
        while(root!=null) {
            if( Math.abs(root.val - target) < min  ) {
                min = Math.abs(root.val - target);
                closest = root.val;
            }
            
            if(target < root.val) {
                root = root.left;
            } else if(target > root.val) {
                root = root.right;
            } else {
                return root.val;
            }
        }
        
        return closest;
    }
}