530. Minimum Absolute Difference in BST

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

Example:

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.

class Solution(object):
    def getMinimumDifference(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        list = []
        def preorder(temp):
            if temp == None:
                return
            list.append(temp.val)
            preorder(temp.left)
            preorder(temp.right)
        preorder(root)
        m = 9999999
        list.sort()
        for i in range(len(list)-1):
            m = min(list[i+1] - list[i],m)
        return m

求的是任意两个节点之间的最小值，先序遍历把数组保存下来，排序之后遍历一遍。