本文共 1217 字，大约阅读时间需要 4 分钟。

第一次，不过

import java.util.Scanner;public class Main {	public static void main(String[] args) {		// TODO Auto-generated method stub		Scanner sc=new Scanner(System.in);		int n=sc.nextInt();		 String result = Integer.toBinaryString(n);	//	 System.out.println(result);		 String reverse = new StringBuffer(result).reverse().toString();	//	 System.out.println(reverse);		 int num=Integer.parseInt(reverse,2);		 System.out.println(num);	}}

修改为biginteger后

import java.math.BigInteger;import java.util.Scanner;public class Main {	public static void main(String[] args) {		// TODO Auto-generated method stub		Scanner sc=new Scanner(System.in);		/*int n=sc.nextInt();		 String result = Integer.toBinaryString(n);		 System.out.println(result);		 String reverse = new StringBuffer(result).reverse().toString();		 System.out.println(reverse);		 int num=Integer.parseInt(reverse,2);		 System.out.println(num);*/		 String input=sc.nextLine();		 String str = new BigInteger(input, 10).toString(2);		 String reverse = new StringBuffer(str).reverse().toString();		// System.out.println(str);		// System.out.println(reverse);		 BigInteger bigInteger = new BigInteger(reverse, 2);         System.out.println(bigInteger);	}}

Java 自带的函数还是很强大的

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