810. 黑板异或游戏 一个黑板上写着一个非负整数数组 nums[i] .小红和小明轮流从黑板上擦掉一个数字,小红先手.如果擦除一个数字后,剩余的所有数字按位异或运算得出的结果等于 0 的话,当前玩家游戏失败. (另外,如果只剩一个数字,按位异或运算得到它本身:如果无数字剩余,按位异或运算结果为 0.) 换种说法就是,轮到某个玩家时,如果当前黑板上所有数字按位异或运算结果等于 0,这个玩家获胜. 假设两个玩家每步都使用最优解,当且仅当小红获胜时返回 true. 示例: 输入: nums = [1…

We are given non-negative integers nums[i] which are written on a chalkboard.  Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting first.  If erasing a number causes the bitwise XOR of all the elements of the…

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1…

Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by performing this transformation. For example: Given "aacecaaa", return "aaacecaaa&qu…

Given a 2D board and a list of words from the dictionary, find all words in the board. Each word must be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same le…

Design a data structure that supports the following two operations: void addWord(word)bool search(word) search(word) can search a literal word or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.…

There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a l…

题目链接: 1661 黑板上的游戏 Alice和Bob在黑板上玩一个游戏,黑板上写了n个正整数a1, a2, ..., an,游戏的规则是这样的:1. Alice占有先手主动权.2. 每个人可以选取一个大于1的数字擦去,并写上一个更小的数字,数字必须是整数,然后由对方进行下一次操作.3. 如果擦去的数字是 x (x > 1) ,则写上的数字不能比 x/k 小,但是要比 x 小.这里的除法为有理数除法.4. 不可以擦去任何一个数字 1 ,如果当前无法找到一个数字进行操作,则当前方输.假设Alice…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most k transactions. 解题思路: https://leetcode.com/discuss/18330/is-it-best-solution-with-o-n-o-1…