leisurehippo的博客

题目如下： You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone will

题目如下： Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. 不让用加号或者减号，自然想到了一些逻辑操作，与或非，异或等等。一位数相加无非是四种可能 a b a+b 0 0 0 0 1 1 1 0 1 1

题目如下： Given an array of integers, every element appears twice except for one. Find that single one. 考虑怎么能把一个数组中两个相同的数字“消”掉呢？ N^N=0 也就是异或。而0^N=N，那么将数组中的数字全部异或最后剩下的数就是答案，算法如下：public class Solution {

题目如下： Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. For example: Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only o

问题描述： Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution.如果简单的遍历两次数组，时间复杂度过大。 一个

题目如下： Write a function that takes a string as input and returns the string reversed. Example: Given s = “hello”, return “olleh”. 基本思路就是将字符串转成数组再逆序拼接成字符串。但是如果用String存储字符串耗时很大。String对象是不可改变的。每次使用 Syste