HDOJ 1002

实现大整数运算，完成bigInteger类封装。

#include  <iostream>
#include <string>
#include <cstdio>
#include <iomanip>

using namespace std;
const int N = 1000;
class bigInteger
{
    friend ostream& operator<<(ostream& out, const bigInteger &A);
public:
    bigInteger()
    {
        for(int i=0; i<N; ++i)
            digit[i] = 0;
        size = 0;
    }
    void set(string s);
    bigInteger operator+(const bigInteger &B);

private:
    int digit[N];
    int size;
};

ostream& operator<<(ostream& out,const bigInteger &A)
{
    for(int i=A.size-1; i>=0; --i)
        if (i!= A.size-1)
            out << setfill('0') << setw(4) << A.digit[i];
        else
            out << A.digit[i];
    return out;
}

void bigInteger::set(string str)
{
    int len = str.size();
    
    int j = 0, c = 1;
    int t=0;
    for(int i=len-1; i>=0; --i) {
        t += (str[i]-'0')*c;
        j++;
        c *= 10;
        if (j == 4 || i == 0) {
            digit[size++] = t;
            j = 0;
            c = 1;
            t = 0;
        }
    }
}

bigInteger bigInteger::operator+(const bigInteger &B)
{
    bigInteger ret;
    int carry = 0;
    for(int i=0; i<size || i<B.size; ++i) {
        int temp = digit[i] + B.digit[i] + carry;
        carry = temp / 10000;
        temp %= 10000;
        ret.digit[ret.size++] = temp;
    }
    if (carry != 0) {
        ret.digit[ret.size++] = carry;
    }
    return ret;
}
int main()
{
#ifdef LOCAL
    freopen("data.txt","r",stdin);
    freopen("data.out","w",stdout);
#endif
    int cases;
    cin >> cases;
    for(int i=0; i<cases; ++i) {
        bigInteger a,b,c;
        string s1,s2;
        cin >> s1 >> s2;
        a.set(s1);
        b.set(s2);
        c = a+b;
        cout << "Case " << i+1 << ":" << endl;
        cout << a << " + " << b << " = " << c << endl;
        if (i < cases-1)
            cout << endl;
    }
    return 0;
}