【LeetCode】783. Minimum Distance Between BST Nodes 解题报告（Python）

【LeetCode】783. Minimum Distance Between BST Nodes 解题报告（Python）

标签（空格分隔）： LeetCode

题目地址：https://leetcode.com/problems/minimum-distance-between-bst-nodes/description/

题目描述：

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.

题目大意

求BST的两个节点之间的最小差值。

解题方法

看见BST想中序遍历是有序的啊~所以先进性中序遍历，得到有序列表，然后找出相邻的两个节点差值的最小值即可。

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def minDiffInBST(self, root):
"""
:type root: TreeNode
:rtype: int
"""
vals = []
def inOrder(root):
if not root:
return
inOrder(root.left)
vals.append(root.val)
inOrder(root.right)
inOrder(root)
return min([vals[i + 1] - vals[i] for i in xrange(len(vals) - 1)])

Date

2018 年 2 月 28 日