You have n problems. You have estimated the difficulty of the i-th one as integer c**i. Now you want to prepare a problemset for a contest, using some of the pr...

最近在做codeforces上面的题，感觉质量挺高的，而且区分难易，便于入手。今天做到的这题考察的东西不少，由于本人水平不济（其实是懒），只能看看别人写的代码，找到一个写的挺好的，多多学习。...

pandas是python数据分析必备工具，它有强大的数据清洗能力，往往能用非常少的代码实现较复杂的数据处理

描述 A game database contains two tables, player table and recharge table. Write a SQL query to find all players who never recharge.

Given two sequences of numbers : a[1], a[2], ...... , a[N], and b[1], b[2], ...... , b[M] (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number ...

Problem Description Write a program to read in a list of integers and determine whether or not each number is prime. A number, n, is prime if its only divisor...

Problem Description One day, winnie received a box and a letter. In the letter, there are three integers and five operations(+,-,*,/,%). If one of the three i...

Problem Description We once did a lot of recursional problem . I think some of them is easy for you and some if hard for you. Now there is a very easy probl...

Problem Description Ignatius was born in a leap year, so he want to know when he could hold his bi

Problem Description Given a positive integer N, you should output the most right digit of N^N.