LeetCode 783. Minimum Distance Between BST Nodes

Description

https://leetcode.com/problems/minimum-distance-between-bst-nodes/

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

Example 1:

Input: root = [4,2,6,1,3]
Output: 1

Example 2:

Input: root = [1,0,48,null,null,12,49]
Output: 1

Constraints:

• The number of nodes in the tree is in the range [2, 100].
• 0 <= Node.val <= 105

Note: This question is the same as 530: https://leetcode.com/problems/minimum-absolute-difference-in-bst/

Explanation

In order traverse to get values in ascending order. Then find the minimum distance between values.

Python Solution

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
def minDiffInBST(self, root: TreeNode) -> int:
self.values = []

self.inorder_traverse(root)

min_distance = sys.maxsize

prev = None

for val in self.values:
if prev:
distance = val - prev
min_distance = min(min_distance, distance)
prev = val

return min_distance

def inorder_traverse(self, root):

if not root:
return

self.inorder_traverse(root.left)
self.values.append(root.val)

self.inorder_traverse(root.right)

• Time Complexity: O(N).
• Space Complexity: O(N).