再难也要坚持

Problem description Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array. Exam

Problem description Write a function that takes a string as input and returns the string reversed. Example: Given s = "hello", return "olleh". 题目描述： 编写一个函数，输入是一个字符串，输出是该字符串的逆序。 例子： 输入：“Hello”，返

Problem description Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. 题目描述 计算两个整数a与b的和，但是你不能使用+、－运算 例子

Problem description Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you imple

Problem description 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 l

字典序法的描述如下： 设P是1～n的一个全排列:p=p1p2……pn=p1p2……pj-1pjpj+1……pk-1pkpk+1……pn 从排列的右端开始，找出第一个比右边字符小的字符的序号j（j从左端开始计算），即 j=max{i|pi