530. Minimum Absolute Difference in BST

📋 Đề Bài

Given the root of a Binary Search Tree (BST), return the minimum absolute 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, 10⁴].
0 <= Node.val <= 10⁵

Note: This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/

🧠 Thuật Toán & Kỹ Thuật

DFS (Tìm kiếm theo chiều sâu)Tree Traversal (Duyệt cây)

⏱️ Thời gian O(V+E)

💾 Không gian O(V)

💻 Lời Giải

Python 0530-minimum-absolute-difference-in-bst.py

# 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 getMinimumDifference(self, root: Optional[TreeNode]) -> int:
        self.res = inf
        self.pre = -inf
        def dfs(root):
            if root.left:
                dfs(root.left)
            
            self.res = min(self.res, root.val - self.pre)
            self.pre = root.val
            
            if root.right:
                dfs(root.right)
                
        dfs(root)
        
        return self.res