leetcode 530. Minimum Absolute Difference in BST（python）

描述

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

Example 1:

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).

Note:

There are at least two nodes in this BST.
This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/

解析

根据题意，就是找出任意两个节点的值的最小值。解决思路也比较简单，用中序遍历将所有的值放入列表中，然后按顺序遍历列表计算出最小差值即可。可以优化的思路是将最后遍历计算最小差值的步骤就放入递归里面，在递归的时候就顺便计算了。

解答

class Solution(object):
    def getMinimumDifference(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        self.result = float("inf")
        self.nodes = []
        def inOrder(root):
            if not root: return
            inOrder(root.left)
            self.nodes.append(root.val)
            inOrder(root.right)
        inOrder(root)
        for i in range(1, len(self.nodes)):
            self.result = min(self.result, self.nodes[i]- self.nodes[i-1])
        return self.result

运行结果

Runtime: 40 ms, faster than 97.70% of Python online submissions for Minimum Absolute Difference in BST.
Memory Usage: 17.6 MB, less than 27.59% of Python online submissions for Minimum Absolute Difference in BST.

原题链接：https://leetcode.com/problems/minimum-absolute-difference-in-bst/

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