上交考研复试07年PowerfulCalculator

题目链接：http://ac.jobdu.com/problem.php?pid=1037

（微难，调了好久，苦难才刚刚开始，加油！）

当然Java代码极其简单

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

public class Main {
    public static void main(String[] args) {
        BigInteger a,b;
        Scanner cin=new Scanner(new BufferedInputStream(System.in));
        while(cin.hasNext()){
            a=cin.nextBigInteger();
            b=cin.nextBigInteger();
            System.out.println(a.add(b));
            System.out.println(a.subtract(b));
            System.out.println(a.multiply(b));
        }
    }

}

#include 
#include 
#include 

using namespace std;

string add(string aa,string bb)
{
string x,y,z;
x = aa;
y = bb;
int la,lb,lc,ztmp;
la = x.length();
lb = y.length();
reverse(x.begin(),x.end());//倒置函数
reverse(y.begin(),y.end());
int jinwei=0;
lc = la>lb?la:lb;
//int flag=0;
z.resize(0);
for(int i=0;i{
if(i{
ztmp = jinwei + (x[i]-'0')+(y[i]-'0');
jinwei = ztmp/10;
}
else if(i>=la&&i{
ztmp = jinwei + (y[i]-'0');
jinwei = ztmp/10;
}
else if(i>=lb&&i{
ztmp = jinwei + (x[i]-'0');
jinwei = ztmp/10;
}
z.push_back('0' + ztmp%10);
if(i==lc-1){
z.push_back(jinwei + '0');
jinwei = 0;
        }
}
reverse(z.begin(),z.end());
return z;


}
string sub(string a,string b)
{
string x,y,z;
x=a;
y=b;
reverse(x.begin(),x.end());
reverse(y.begin(),y.end());
z.resize(0);
int borrow = 0;
bool sign = false;
int tmp;
if(x.length(){
swap(x,y);
sign = true;
}
else if(x.length() == y.length())
{
for(int i= x.length()-1;i>=0;i--)
{
if(x[i]{
swap(x,y);
sign = true;
break;
}
}
}
for(int i=0;i{
if(i{
tmp = (x[i]-'0')-(y[i]-'0') - borrow;
if(tmp<0)
{
tmp = tmp + 10;
borrow = 1;
z.push_back('0'+tmp);
}
else
{
z.push_back('0'+tmp);
borrow = 0;
}
}
else
{
//cout<tmp =  (x[i] - '0') - borrow;
if(tmp<0)
{
tmp = tmp + 10;
borrow = 1;
z.push_back('0'+tmp);
}
else
{
z.push_back('0'+tmp);
borrow = 0;
}
}
}
if(sign)
{
z = z + '-';
}
reverse(z.begin(),z.end());
return z;

}

string mul(string a,string b)
{
string x,y,z;
x = a;
y = b;
int la,lb;

la = x.length();
lb = y.length();
z.resize(la+lb);
for(int i=0;i{
z[i] = '0';
}
int jinwei =0,tmp;
reverse(x.begin(),x.end());
reverse(y.begin(),y.end());
for(int i=0;i{
for(int j=0;j{
tmp = jinwei +(x[i]-'0')*(y[j]-'0') + (z[i+j]-'0');
z[i+j] = '0' + tmp%10;
jinwei = tmp/10;
if(j==lb-1)
{
z[i+j+1] = '0' + jinwei;
jinwei = 0;
}
}
}
reverse(z.begin(),z.end());
return z;
}
void printf(string c)
{
if(c[0]=='-')
{
cout<for(int i=1;i{
cout<}
}
else if(c[0]=='0'&&c.length()==1)
{
cout<}
else if(c[0] == '0'&&c[1]=='0')
{
cout<<'0';
}
else if(c[0] == '0')
{
for(int i=1;i{
cout<}
}
else if(c[0]!=0)
{
cout<for(int i=1;i{
cout<}
}
cout<
}
int main()
{
string a,b,c;
while(cin>>a>>b)
{
c = add(a,b);
printf(c);
c = sub(a,b);
printf(c);
c = mul(a,b);
printf(c);
}
return 0;
}