leetcode-530-Minimum-Absolute-Difference-in-BST

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描述

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.

Example:

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Input:

   1
    \
     3
    /
   2

Output:
1

Explanation:
The minimum absolute difference is 1, which is the difference between 2 and 1 (or between 2 and 3).

分析

求二叉树相邻节点间差值绝对值的最小值。因为中序遍历的结果是有序的，用中序遍历即可。

解决方案1(Java)

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/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    private int result;
    private int prev;
    
    public int getMinimumDifference(TreeNode root) {
        result = Integer.MAX_VALUE;
        prev = Integer.MAX_VALUE;
        inOrder(root);
        return result;
    }
    
    private void inOrder(TreeNode root) {
        if (root == null) {
            return;    
        }
        inOrder(root.left);
        result = Math.min(result, Math.abs(root.val-prev));
        prev = root.val;
        inOrder(root.right);
    }
}

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