UVA 10106-Product(大數乘法)

Description

Product

The Problem

The problem is to multiply two integers X, Y. (0<=X,Y<10²⁵⁰)

The Input

The input will consist of a set of pairs of lines. Each line in pair contains one multiplyer.

The Output

For each input pair of lines the output line should consist one integer the product.

Sample Input

12
12
2
222222222222222222222222

Sample Output

144
444444444444444444444444

注意當為0的情況，一開始忽略了這種情況。當任一個為0的時候別忘了輸出0

#include
#include
#include
char str1[1010],str2[1010];
char a[1010],b[1010],sum[1010];
int main()
{
    int len1,len2;
    int i,j;
    while (~scanf("%s",str1))
    {
        memset(a,0,sizeof(a));
        memset(b,0,sizeof(b));
        memset(sum,0,sizeof(sum));
        len1= strlen(str1);
        for (i=len1-1;i>=0;i--)
            a[len1-i-1]=str1[i]-'0';
        scanf("%s",str2);
        len2=strlen(str2);
        for (i=len2-1;i>=0;i--)
            b[len2-i-1]=str2[i]-'0';
        for (i=0;i=10)
                {
                    sum[j+1]+=sum[j]/10;
                    sum[j]%=10;
                }
        }
        int flag=0;
        for(i=1010;i>=0;i--)
        {
            if(flag||sum[i])
            {
                flag=1;
                printf("%d",sum[i]);
            }
        }
        if(!flag)
            printf("0");
        printf("\n");
    }
    return 0;
}