北叶青藤

摘要： Given the root of a binary tree, determine if it is a complete binary tree. In a complete binary tree, every level, except possibly the last, is compl 阅读全文

摘要： Given a string s, a k duplicate removal consists of choosing k adjacent and equal letters from s and removing them causing the left and the right side 阅读全文

摘要： Given a string s containing only three types of characters: '(', ')' and '*', return true if s is valid. The following rules define a valid string: An 阅读全文

摘要： Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus 阅读全文

摘要： There are n buildings in a line. You are given an integer array heights of size n that represents the heights of the buildings in the line. The ocean 阅读全文

摘要： Some people will make friend requests. The list of their ages is given and ages[i] is the age of the ith person. Person A will NOT friend request pers 阅读全文

摘要： Given an array of integers nums, calculate the pivot index of this array. The pivot index is the index where the sum of all the numbers strictly to th 阅读全文

摘要： Given a node from a Circular Linked List which is sorted in ascending order, write a function to insert a value insertVal into the list such that it r 阅读全文

摘要： Given an unsorted array of integers nums, return the length of the longest continuous increasing subsequence (i.e. subarray). The subsequence must be  阅读全文

摘要： Given an integer array arr, remove a subarray (can be empty) from arr such that the remaining elements in arr are non-decreasing. A subarray is a cont 阅读全文