1503 Integer Inquiry

Integer Inquiry

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 25308		Accepted: 9827

Description

One of the first users of BIT's new supercomputer was Chip Diller. He extended his exploration of powers of 3 to go from 0 to 333 and he explored taking various sums of those numbers. 
``This supercomputer is great,'' remarked Chip. ``I only wish Timothy were here to see these results.'' (Chip moved to a new apartment, once one became available on the third floor of the Lemon Sky apartments on Third Street.) 

Input

The input will consist of at most 100 lines of text, each of which contains a single VeryLongInteger. Each VeryLongInteger will be 100 or fewer characters in length, and will only contain digits (no VeryLongInteger will be negative). 

The final input line will contain a single zero on a line by itself. 

Output

Your program should output the sum of the VeryLongIntegers given in the input.

Sample Input

1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678900

Sample Output

370370367037037036703703703670

Source

East Central North America 1996大數加法，10年的時候就看到華科複試有這麼個題目，原來還是有出處的。顯然用c/c++甚至java中內建的任何資料類型都不行，都會超出範圍。只能用字串儲存輸入資料了，而計算過程就需要自己類比加法過程，一位一位的加，考慮進位等。用棧實現起來較為方便，當然自己用數組也行。後面應該還有高精度（浮點數）乘法，原理類似。代碼如下：

#include <iostream>#include <stack>using namespace std;string add(const string &a, const string &b){    //string res;    stack<char> sa,sb,sc;    int carry=0;    size_t its=0;    while(its!=a.length())    {        sa.push(a[its]);        its++;    }    its=0;    while(its!=b.length())    {        sb.push(b[its]);        its++;    }    while(!sa.empty() && !sb.empty())    {        int t = sa.top()-'0' + sb.top()-'0'+carry;        if(t>9)        {            carry = 1;            t -= 10;        }        else        {            carry = 0;        }        sc.push(t+'0');        sa.pop();        sb.pop();    }    while(!sa.empty())    {        int t = sa.top()-'0'+carry;        if(t>9)        {            carry = 1;            t -= 10;        }        else        {            carry =0;        }        sc.push(t+'0');        sa.pop();    }    while(!sb.empty())    {        int t = sb.top()-'0'+carry;        if(t>9)        {            carry = 1;            t -= 10;        }        else        {            carry=0;        }        sc.push(t+'0');        sb.pop();    }    if(carry)        sc.push('1');    string res;    while(!sc.empty())    {        res.push_back(sc.top());        sc.pop();    }    return res;}int main(){    string str;    string res;    while(cin>>str)    {        if(str=="0")            break;        res=add(res,str);    }    cout<<res<<endl;    return 0;}