Happy Coding

This blog is for my memorandum about programming and English.

Happy Coding

This blog is for my memorandum

binary search tree

Contains Duplicate III

problem Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k. h…

Validate BST

problem Implement a function to check if a binary tree is a binary search tree. how to solve Binary search tree means that all left nodes must be less than or equal to the current node and all right nodes must be more than or equal to the …