摘要：
The set S originally contains numbers from 1 to n. But unfortunately, due to the data error, one of the numbers in the set got duplicated to another n 阅读全文
摘要：
Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... Note:n is positive and will fit within the range of a 32-bi 阅读全文
摘要：
Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c. Example 1: Example 2: 阅读全文
摘要：
We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself. Now, given an integer n, write 阅读全文
摘要：
Given a non-empty integer array of size n, find the minimum number of moves required to make all array elements equal, where a move is incrementing n 阅读全文
摘要：
You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins. Given n, find the total number 阅读全文
摘要：
Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2. Note: 求两个字符串的加法 阅读全文
摘要：
Given a positive integer num, write a function which returns True if num is a perfect square else False. 题目含义：判断一个数能否被开方 阅读全文
摘要：
Given an integer, write a function to determine if it is a power of three. 题目含义：给定一个数，判断它是否是3的n次方 思路：使用换底公式 阅读全文
摘要：
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: 阅读全文
摘要：
Given an integer, write a function to determine if it is a power of two. 题目含义：判断一个数是否是2的n次方 阅读全文
摘要：
ount the number of prime numbers less than a non-negative number, n. 题目含义：要求计算小于N的所有素数的个数。素数又称质数，是只能被1和自身整数的数 思路：厄拉多塞筛法 西元前250年，希腊数学家厄拉多塞(Eeatosthese) 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：
Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 题目含义：这里我们要求n!末尾有多少个0 思路： 阅读全文
摘要：
Related to question Excel Sheet Column Title Given a column title as appear in an Excel sheet, return its corresponding column number. For example: 阅读全文
摘要：
Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: 阅读全文
摘要：
Implement int sqrt(int x). Compute and return the square root of x. 题目题目：返回一个int数开方后的结果 阅读全文
摘要：
Given a non-negative integer represented as a non-empty array of digits, plus one to the integer. You may assume the integer do not contain any leadin 阅读全文
摘要：
Determine whether an integer is a palindrome. Do this without extra space. 题目含义：不要使用额外空间，判断整数是否为回文 阅读全文
摘要：
Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 题目含义翻转一个整数 相关题目：190. Reverse Bits 阅读全文