摘要：You are given a string s containing lowercase English letters, and a matrix shift, where shift[i] = [direction, amount]: direction can be 0 (for left 阅读全文

摘要：Given a binary array, find the maximum length of a contiguous subarray with equal number of 0 and 1. Example 1: Example 2: Note: The length of the giv 阅读全文

摘要：We have a collection of stones, each stone has a positive integer weight. Each turn, we choose the two heaviest stones and smash them together. Suppos 阅读全文

摘要：Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path betwe 阅读全文

摘要：Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) Push element x onto stack. pop() Removes the 阅读全文

摘要：Given two strings S and T, return if they are equal when both are typed into empty text editors. means a backspace character. Example 1: Example 2: Ex 阅读全文

摘要：Given a non empty, singly linked list with head node head, return a middle node of linked list. If there are two middle nodes, return the second middl 阅读全文

摘要：Given an integer array arr, count element x such that x + 1 is also in arr. If there're duplicates in arr, count them seperately. Example 1: Example 2 阅读全文

摘要：Given an array of strings, group anagrams together. Example: Note: All inputs will be in lowercase. The order of your output does not matter. 这道题就是用每个 阅读全文

摘要：Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction 阅读全文

摘要：Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non zero elements. Example: Input: 阅读全文

摘要：Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum. Example: Inpu 阅读全文

摘要：Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive intege 阅读全文

摘要：从今天开始努力刷题，用这个帖子来记录刷题的进度。也方便自己的寻找。 题号 题目 复习 1 Two Sum Y 2 Add Two Numbers Y 3 Longest Substring Without Repeating Characters Y 4 Median of Two Sorted A 阅读全文

摘要：Given a non-empty array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runti 阅读全文

摘要：这道题虽然简单，但是需要注意的点还是比较多，首先是如果一直有重复的duplicate，要把所有的都去掉，所以inner loop是while而不是if，其次是每一层loop结束的条件，要搞清楚是head，还是head.next是不是None。 最后学习一下在python中如何建立一个class并且写 阅读全文

摘要：很简单的杨辉三角问题，时间复杂度是O(N), 空间复杂度是O(1) class Solution: def generate(self, numRows: int) -> List[List[int]]: if numRows == 0: return [] result = [[1]] for r 阅读全文

摘要：这道题其实和其他类似问题很相似，就是要处理carry的问题。时间复杂度是O(N)，空间复杂度是O(1) class Solution: def addBinary(self, a: str, b: str) -> str: i, j, carry = len(a) - 1, len(b) - 1, 阅读全文

摘要：这道题非常简单，就是双指针问题的基础版，时间复杂度是O(N),空间复杂度是O(1) class Solution: def reverseString(self, s: List[str]) -> None: """ Do not return anything, modify s in-place 阅读全文

摘要：这道题的时间复杂度是O(N), 空间复杂度也是O(N) 这道题也是matrix的遍历，只是遍历的顺序是sprial，这种题的模版就是写出变化的delta，然后check新的点是不是在matrix的范围内，加上其他条件，这道题的条件是是否已经visit过，当满足就会发生一些变化，比如方向的变化。还有一 阅读全文