# LeetCode.783.Minimum Distance Between BST Nodes BST的最小差值

## 题目描述

783 Minimum Distance Between BST Nodes
https://leetcode-cn.com/problems/minimum-distance-between-bst-nodes/

Given a Binary Search Tree (BST) with the root node root, return the minimum difference between the values of any two different nodes in the tree.

Example :

Input: root = [4,2,6,1,3,null,null]
Output: 1
Explanation:
Note that root is a TreeNode object, not an array.

The given tree [4,2,6,1,3,null,null] is represented by the following diagram:

4
/   \
2      6
/ \
1   3

while the minimum difference in this tree is 1, it occurs between node 1 and node 2, also between node 3 and node 2.

Note:
The size of the BST will be between 2 and 100.
The BST is always valid, each node’s value is an integer, and each node’s value is different.

## 解题过程

LeetCode.530.Minimum Absolute Difference in BST 非负BST的最小绝对差

private static class SolutionV2020 {
private Long minDiff;
private TreeNode pre;
public int minDiffInBST(TreeNode root) {
minDiff = Long.MAX_VALUE;
pre = null;
inOrder(root);
return minDiff.intValue();
}

// 中序遍历，过程中更新minDiff
private void inOrder(TreeNode root) {
if (null == root) {
return;
}
inOrder(root.left);
if (null != pre) {
minDiff = Math.min(minDiff, (long)root.val - (long)pre.val);
}
pre = root;
inOrder(root.right);
}
}

## GitHub代码

algorithms/leetcode/leetcode/_783_MinimumDistanceBetweenBSTNodes.java
https://github.com/masikkk/algorithms/blob/master/leetcode/leetcode/_783_MinimumDistanceBetweenBSTNodes.java

406

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