Java & C++ 大数计算

Java--大数计算,妈妈再也不用担心我的学习了 .

BigInteger

英文API：

http://docs.oracle.com/javase/8/docs/api/

中文API：

http://tool.oschina.net/apidocs/apidoc?api=jdk-zh

import java.math.BigInteger;
import java.util.Scanner;

//hdu 1002----A + B Problem II

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int i = 1;
		while (n-- != 0) {
			BigInteger a = new BigInteger(sc.next());
			BigInteger b = new BigInteger(sc.next());
			System.out.println("Case " + (i++) + ":");
			System.out.println(a + " + " + b + " = " + a.add(b));
			if (n != 0)
				System.out.println();
		}
	}
}

　

import java.math.BigInteger;
import java.util.Scanner;

//hdu 1042 N!

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while (sc.hasNext()) {
			BigInteger a = new BigInteger(sc.next());

			if (a.compareTo(new BigInteger("0")) == 0) {
				// 如果是0 返回1
				System.out.println("1");
				continue;
			}

			BigInteger sum = a;
			// 举例 求 9！ 这是 sum=a=9

			BigInteger b = new BigInteger("1");

			while (a.compareTo(b) != 0) {
				// while a不等于1
				// 第一次循环sum=9 sum=sum*8(a=a-1)a=8
				// 第二次循环 sum=72，sum=sum*7(a=a-1)a=7
				// 第三次循环 sum=504，sum=sum*6(a=a-1)a=6
				// .....等于1时退出
				sum = sum.multiply(a = a.subtract(b));
			}
			System.out.println(sum);
		}
	}
}

　-C++

string add(string str1,string str2)
{
    string str;
    int len1=str1.length();
    int len2=str2.length();
    if(len1<len2) {
        for(int i=1; i<=len2-len1; i++)
            str1="0"+str1;
    } else {
        for(int i=1; i<len1-len2; i++) {
            str2="0"+str2;
        }
    }
    len1=str1.length();
    int cf=0;
    int tem;
    for(int i=len1-1; i>=0; i--) {
        tem=str1[i]-'0'+str2[i]-'0'+cf;
        cf=tem/10;
        tem%=10;
        str=char(tem+'0')+str;
    }
    if(cf!=0)str=char(cf+'0')+str;
    return str;
}