【Java】Java划水练习

bzoj1000 A+B Problem

Scanner sc=new Scanner(new BufferedInputStream(System.in)); 声明读入器

nextInt 读入整数

System.out.println 带换行输出

import java.util.*;
import java.io.*;

public class Main{
	public static void main(String[] argc){
		Scanner sc = new Scanner (new BufferedInputStream(System.in));
		int a=sc.nextInt(),b=sc.nextInt();
		System.out.println(a+b);
		sc.close();
    }
}

poj1503 Integer Inquiry

BigInteger.ZERO 大整数常量零

equals 相等

add 加

import java.util.*;
import java.io.*;
import java.math.*;

public class Main{
	public static void main(String[] argc){
		Scanner sc = new Scanner (new BufferedInputStream(System.in));
		BigInteger sum=BigInteger.ZERO;
		while(true){
			BigInteger x=sc.nextBigInteger();
			if(x.equals(BigInteger.ZERO)){
				break;
			}
			sum=sum.add(x);
		}
		System.out.println(sum);
		sc.close();
    }
}

poj1001 求高精度幂

stripTrailingZeros 清除不影响大小的零

toPlainString 以朴素的方式（而非科学计数法或工程计数法）将BigDecimal转换成String

hasNext 判断是否读入完成

next 读入字符串，直到空格为止

nextLine 读入一整行字符串

public String substring(int beginIndex) 返回该字符串从beginIndex开始到结尾的子字符串；

public String substring(int beginIndex,int endIndex) 返回该字符串从beginIndex开始到endsIndex结尾的子字符串

import java.util.*;
import java.io.*;
import java.math.*;

public class Main {
	public static void main(String[] argc){
		Scanner sc=new Scanner(new BufferedInputStream(System.in));
		while(sc.hasNext()){
			String s=sc.next();
			int n=sc.nextInt();
			BigDecimal x=new BigDecimal(s);
			s=x.pow(n).stripTrailingZeros().toPlainString();
			if(s.charAt(0)=='0'){
				s=s.substring(1);
			}
			System.out.println(s);
		}
		sc.close();
	}
}

bzoj1876 [SDOI2009]SuperGCD

gcd 求两个大整数的gcd

import java.util.*;
import java.io.*;
import java.math.*;

public class Main {
	public static void main(String[] argc){
		Scanner sc=new Scanner(new BufferedInputStream(System.in));
		BigInteger a=sc.nextBigInteger();
		BigInteger b=sc.nextBigInteger();
		System.out.println(a.gcd(b));
		sc.close();
	}
}