[NOIP 2003 普及组] 麦森数 Java

import java.util.*;
import java.math.BigInteger;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int p = sc.nextInt();sc.close();int num = (int) Math.floor(p * Math.log10(2)) + 1; // 位数BigInteger mod = BigInteger.TEN.pow(500); // 求最后500位，对10^5取模即可BigInteger bi = BigInteger.valueOf(2).pow(p).subtract(BigInteger.ONE).mod(mod); // 求出2^p-1并取模String str = bi.toString();while (str.length() < 500) {str = "0" + str; // 补充高位0}StringBuilder sb = new StringBuilder();sb.append(num + "\n");for (int i = str.length() - 500; i < str.length(); i += 50) {sb.append(str.substring(i, i + 50) + "\n");}System.out.println(sb);}
}

每日一水~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~