1e9 以内的判断一个数是否是素数,可以直接朴素的暴力. 这倒题除了考虑1e9以内的素数的判断,还有一个歌德巴赫猜想:任意一个奇数都可一分解为三个素数的和. 第三个结论:素数是密集的,1e9以内,相邻的素数之间的间隔不会大于300,所以直接枚举也不会浪费掉太多的时间. 这里还有一点需要注意的是:朴素的判断是否是素数,i<=saqrt(n).今天的天梯赛由于记错了这个条件,导致没有求出素数,一道二十分的题没有做,好伤心. Dima and Lisa Time Limit:1000MS …
D. Dima and Lisa Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/problem/D Description Dima loves representing an odd number as the sum of multiple primes, and Lisa loves it when there are at most three primes. Help them…
D. Dima and Lisa Dima loves representing an odd number as the sum of multiple primes, and Lisa loves it when there are at most three primes. Help them to represent the given number as the sum of at mos…
B. Little Dima and Equation time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Little Dima misbehaved during a math lesson a lot and the nasty teacher Mr. Pickles gave him the following proble…
Problem description Dima loves representing an odd number as the sum of multiple primes, and Lisa loves it when there are at most three primes. Help them to represent the given number as the sum of at most than three primes. More formally, you are gi…