大数相乘 小小优化版本

#include <iostream>#include <string>#include <cstring>#include <stdio.h>using namespace std;short int a[1005],b[1005],c[2005][2005];char e[1005],e2[1005];int main(){    int i,j;    int x,y;    cin>>e>>e2;    x=strlen(e);    y=strlen(e2);    cout<<x<<y<<endl;    for(i=0;i<x;i++) {a[i]=e[i]-48;}    for(i=0;i<y;i++) {b[i]=e2[i]-48;}    memset(c,0,sizeof(c));    for(i=0;i<y;i++)    {        int n=x+y-i;        int z=0;        for(j=0;j<x;j++)        {            c[i][n]=((a[x-1-j]*b[y-1-i])+z)%10;            int r=a[x-1-j]*b[y-1-i]+z;            if(r>9) z=r/10;            else z=0;            n=n-1;        }        c[i][n]=z;    }    for(i=0;i<y;i++)    {        for(j=0;j<=x+y;j++)        cout<<c[i][j]<<' ';        cout<<endl;    }    short int d[1005];int z=0;    memset(d,0,sizeof(d));    for(i=x+y;i>=0;i--)    {        d[i]=0;        d[i]=z;        for(j=y-1;j>=0;j--)        {            d[i]=d[i]+c[j][i];        }            if(d[i]>9)            {                z=d[i]/10;                d[i]=d[i]%10;            }            else z=0;    }    for(i=0;;i++)    {        if(d[i]!=0) break;    }    for(;i<=x+y;i++)        cout<<d[i];    cout<<endl;    return 0;}