5309 Product

Problem B: Product

Time Limit: 1 Sec   Memory Limit: 128 MB
Submit: 51   Solved: 15
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Description

The problem is to multiply two integers X, Y. (0<=X,Y<10 ²⁵⁰)

Input

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

Output

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

Sample Input

12
12
2
222222222222222222222222

Sample Output

144444444444444444444444444

HINT

解题报告：

    1、大数乘法，还行

    2、通过一个int数组，存储在每个位置相乘得到的值。

    3、通过细节处理，得到大数相乘的值

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
 
#define Max 550
 
int cake[Max];
char c_a[Max],c_b[Max];
char result[Max];
 
int main() {
    while (~scanf("%s %s",c_a,c_b)) {
        int count=0,i,j;
        memset(cake,0,sizeof(cake));
        memset(result,'\0',sizeof(result));
        int na = strlen(c_a);
        int nb = strlen(c_b);
        for (i=na-1; i>=0; i--) {
            for (j=nb-1; j>=0; j--) {
                cake[i+j+1] = cake[i+j+1] + (c_a[i]-'0') * (c_b[j]-'0');
            }
        }
        for (i=na+nb-1; i>=0; i--) {
            cake[i] = cake[i] + count;
            count = cake[i] / 10;
            cake[i] = cake[i] % 10;
        }
        for (i=0; !cake[i] && i<na+nb-1; i++) {
             
             
        }
        j=0;
        for ( ; i<na+nb; i++) {
            result[j++] = cake[i] + '0';
        }
        printf("%s\n",result);
    }
     
    return 0;
}