大数乘法_讨论帖

[不知名小渣]

#include<bits/stdc++.h>
using namespace std ;

void bigmul(int x , int y ,int r[])
{
int base = 10000 ;
int x2 = x / base ;
int x1 = x% base ;
int y2 = y / base ;
int y1 = y % base ;

int n1 = x1 * y1 ;
int n2 = x1 * y2 ;
int n3 = x2 * y1 ;
int n4 = x2 * y2 ;

r[3] = n1 % base ;
r[2] = n1 / base + n2 % base + n3 % base ;
r[1] = n2 / base + n3 / base + n4 % base ;
r[0] = n4 / base ;

r[1] += r[2] /base ;
r[2] = r[2] % base ;
r[0] += r[1] / base ;
r[1] = r[1] % base ;

}

int main(int argc , char *argv[])
{
int x[ ] ={0, 0, 0, 0} ;
bigmul(87654321 , 12345678 , x);
printf("%d%d%d%d\n",x[0],x[1],x[2],x[3]);
return 0 ;
}