2021十二届蓝桥杯Java B国赛（原题+部分题解）

2024-07-31 05:16:000 次浏览 投稿

前前后后准备了快两个月，还算有所收获，国奖应该能拿个，不过感觉国赛的题比省赛简单的多就很迷

A 整数范围

签到，刚开始还以为有什么坑斟酌了半天

public static void main(String[] args) {String s ="11111111";int x = Integer.parseInt(s,2);System.out.println(x);}

255

B 纯质数

常规题，欧拉筛出质数再遍历一遍判断即可，反正是填空怎么筛都行

package atta;import java.io.*;import java.util.*;public class Main {static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));static Scanner tab = new Scanner(System.in);static int N = 30000010;static int cnt = 0;static int primes[] = new int [N];static boolean st[] = new boolean [N];static void get_primes(int n) {for(int i = 2;i