https://vjudge.net/contest/218366 Java解 import java.math.BigInteger; import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner cin = new Scanner(System.in); BigInteger a = cin.nextBigInteger(); Boolean b = a.isPro…
解题关键: 根据质数的定义,在判断一个数n是否是质数时,我们只要用1至n-1去除n,看看能否整除即可.但我们有更好的办法.先找一个数m,使m的平方大于n,再用<=m的质数去除n(n即为被除数),如果都不能整除,则n必然是质数.如我们要判断1993是不是质数,50*50>1993,那么我们只要用1993除以<50的质数看是否能整除,若不能即为质数. #include<bits/stdc++.h> using namespace std; typedef long long ll…
#In the next recipe, we'll look at how to tune the random forest classifier. #Let's start by importing datasets: from sklearn import datasets X, y = datasets.make_classification(1000) # X(1000,20) #y(1000) 取值范围[0,1] from sklearn.ensemble import Rando…