大数相乘

Bertha 。 2022-08-05 08:54 192阅读 0赞

题目：请使用代码计算1234567891011121314151617181920\*2019181716151413121110987654321。

答：

![复制代码][copycode.gif]

#include "stdafx.h"
    #include <iostream>
    #include <string>
    
    using namespace std;
    
    int _tmain(int argc, _TCHAR* argv[])
    {
        string strOne;
        string strTwo;
        cout<<"输入第一个乘数：";
        cin>>strOne;
        cout<<"输入第二个乘数：";
        cin>>strTwo;
        int lengthOne = strOne.size();
        int lengthTwo = strTwo.size();
        int lengthResult = lengthOne * lengthTwo;
        int *result = new int[lengthResult];
        memset(result, 0, lengthResult * sizeof(int));
    
        int count = 1;
        int i, j, k;
        for (i = lengthTwo - 1; i >= 0; i--)
        {
            k = lengthResult - count;
            for (j = lengthOne - 1; j >= 0; j--)
            {
                result[k--] += (strTwo[i] - '0') * (strOne[j] - '0');
            }
            count++;
        }
    
        for (i = lengthResult - 1; i > 0; i--)
        {
            while(result[i] >= 10)
            {
                result[i] -= 10;
                result[i - 1]++;
            }
        }
        for (i = 0; i < lengthResult; i++)
        {
            if (0 != result[i])
            {
                break;
            }
        }
    
        cout<<strOne<<" * "<<strTwo<<" = "<<endl;
        for (; i < lengthResult; i++)
        {
            cout<<result[i];
        }
    
        delete [] result;
        cout<<endl;
        return 0;
    }

![复制代码][copycode.gif]

运行界面如下：

![2012090419133512.jpg][]

[copycode.gif]: /images/20220731/2f5e753773134e5da882faf36a210d5d.png
[2012090419133512.jpg]: /images/20220731/7cc4f0e684054bc49511ccad3206db86.png