, cy = b[i + j];
double dx = a[i + j + half], dy = b[i + j + half];
double ex = dx * wx - dy * wy, ey = dx * wy + dy * wx;
a[i + j] = cx + ex, b[i + j] = cy + ey;
a[i + j + half] = cx - ex, b[i + j + half] = cy - ey;
double wnx = wx * wmx - wy * wmy, wny = wx * wmy + wy * wmx;
wx = wnx, wy = wny;
}
}
}
if (rev)
{
for (int i = 0; i < n; i++)
a[i] /= n, b[i] /= n;
}
}
int solve(int a[],int na,int b[],int nb,int ans[])
{
int len = max(na, nb), ln;
for(ln=0; L(ln) len=L(++ln);
for (int i = 0; i < len ; ++i)
{
if (i >= na) ax[i] = 0, ay[i] =0;
else ax[i] = a[i], ay[i] = 0;
}
fft(ax, ay, len, 0);
for (int i = 0; i < len; ++i)
{
if (i >= nb) bx[i] = 0, by[i] = 0;
else bx[i] = b[i], by[i] = 0;
}
fft(bx, by, len, 0);
for (int i = 0; i < len; ++i)
{
double cx = ax[i] * bx[i] - ay[i] * by[i];
double cy = ax[i] * by[i] + ay[i] * bx[i];
ax[i] = cx, ay[i] = cy;
}
fft(ax, ay, len, 1);
for (int i = 0; i < len; ++i)
ans[i] = (int)(ax[i] + 0.5);
return len;
}
int main()
{
int l1,l2,l;
int i;
while(gets(sa))
{
gets(sb);
memset(sum, 0, sizeof(sum));
l1 = strlen(sa);
l2 = strlen(sb);
for(i = 0; i < l1; i++)
x1[i] = sa[l1 - i - 1]-'0';
for(i = 0; i < l2; i++)
x2[i] = sb[l2-i-1]-'0';
l = solve(x1, l1, x2, l2, sum);
for(i = 0; i= 10; i++) // 进位
{
sum[i + 1] += sum[i] / 10;
sum[i] %= 10;
}
l = i;
while(sum[l] <= 0 && l>0) l--; // 检索最高位
for(i = l; i >= 0; i--) putchar(sum[i] + '0'); // 倒序输出
putchar('\n');
}
return 0;
}
#include
#include
#include
#include
#include
#include