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| /* ***********************************************
MYID : Chen Fan
LANG : G++
PROG : FFT_HDU_1402
************************************************ */
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define nn 70000
#define snn 60000
using namespace std;
struct gjtype
{
int a[nn];
void clean()
{
memset(a,0,sizeof(a));
}
void ntog(long long s)
{
clean();
int i=0;
while (s>0)
{
i++;
a[i]=s%100;
s=s/100;
}
a[0]=i;
}
void stog(char s1[])
{
clean();
char ss[snn],s[snn];
bool pos=true;
if (s1[0]=='-')
{
strcpy(s,s1+1);
pos=false;
} else strcpy(s,s1);
int i=0;
while (strlen(s)>=2)
{
i++;
for (int j=strlen(s)-2;j<strlen(s);j++)
ss[j-strlen(s)+2]=s[j];
s[strlen(s)-2]='\0';
a[i]=atoi(ss);
}
if (strlen(s)>0)
{
i++;
a[i]=atoi(s);
}
a[0]=i;
if (!pos) a[a[0]]=-a[a[0]];
}
void out()
{
printf("%d",a[a[0]]);
for (int i=a[0]-1;i>=1;i--)
printf("%02d",a[i]);
putchar('\n');
}
};
gjtype a,b,c;
const double PI = acos(-1.0);
struct fstype
{
double x,y;
fstype(double real = 0.0,double imag = 0.0)
{
x = real;
y = imag;
}
fstype operator -(const fstype &b)const
{
return fstype(x-b.x,y-b.y);
}
fstype operator +(const fstype &b)const
{
return fstype(x+b.x,y+b.y);
}
fstype operator *(const fstype &b)const
{
return fstype(x*b.x-y*b.y,x*b.y+y*b.x);
}
};
void fft(fstype y[],int len,int on)
{
int i,j,k;
for(i = 1, j = len/2;i <len-1;i++)
{
if (i < j) swap(y[i],y[j]);
k = len/2;
while(j >= k)
{
j -= k;
k /= 2;
}
if(j < k) j += k;
}
for(int h = 2; h <= len; h <<= 1)
{
fstype wn(cos(-on*2*PI/h),sin(-on*2*PI/h));
for(int j = 0;j < len;j+=h)
{
fstype w(1,0);
for(int k = j;k < j+h/2;k++)
{
fstype u = y[k];
fstype t = w*y[k+h/2];
y[k] = u+t;
y[k+h/2] = u-t;
w = w*wn;
}
}
}
if(on == -1)
for(int i = 0;i < len;i++)
y[i].x /= len;
}
fstype x1[nn],x2[nn];
gjtype cc;
gjtype fftcheng(gjtype aa,gjtype bb)
{
int len1=aa.a[0],len2=bb.a[0],len=1;
while (len<len1*2||len<len2*2) len<<=1;
for (int i=1;i<=len1;i++) x1[i-1]=fstype(aa.a[i],0);
for (int i=len1;i<len;i++) x1[i]=fstype(0,0);
for (int i=1;i<=len2;i++) x2[i-1]=fstype(bb.a[i],0);
for (int i=len2;i<len;i++) x2[i]=fstype(0,0);
fft(x1,len,1);
fft(x2,len,1);
for (int i=0;i<len;i++) x1[i]=x1[i]*x2[i];
fft(x1,len,-1);
cc.clean();
for (int i=0;i<len;i++) cc.a[i+1]=(int)(x1[i].x+0.5);
for (int i=1;i<=len;i++)
{
cc.a[i+1]+=cc.a[i]/100;
cc.a[i]%=100;
}
while(cc.a[len] == 0 && len > 1)len--;
cc.a[0]=len;
return cc;
}
int main()
{
//freopen("1.txt","r",stdin);
//freopen("1.out","w",stdout);
gjtype a,b,c;
char s1[snn],s2[snn];
while (scanf("%s%s",s1,s2)!=EOF)
{
a.stog(s1);
b.stog(s2);
c=fftcheng(a,b);
c.out();
//c=cheng(a,b);
//c.out();
}
return 0;
}
|