func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, a[22][1 << 18], b[22][1 << 18], c[1 << 18], ans[1 << 18];   int M1, M2, M3, M4, N1, N2;   int add(int x, int y) { return (x + y) & M1; }   int mult(int x, int y) {     int z = 0;     int xx = x & N1;     xx |= xx << 1;     z = xx & y;     xx = x & N2;     xx |= xx >> 1;     z ^= (xx & y) << 1;     return z & M1;   }   int zeta(int* a) {     int i, j, k;     for (i = 0; i < n; i++) {       if (i < 3) {         for (j = 0; j < (1 << max(n - 3, 0)); j++) {           if (i == 0)             a[j] = add(a[j], (a[j] & M2) << 4);           else if (i == 1)             a[j] = add(a[j], (a[j] & M3) << 8);           else             a[j] = add(a[j], (a[j] & M4) << 16);         }       } else {         for (j = 0; j < (1 << (n - 3)); j += (1 << (i - 2))) {           for (k = 0; k < (1 << (i - 3)); k++)             a[j ^ k ^ (1 << (i - 3))] = add(a[j ^ k ^ (1 << (i - 3))], a[j ^ k]);         }       }     }     return 0;   }   int main() {     int i;     scanf( %d n , &n);     for (i = 0; i < (1 << n); i++)       a[__builtin_popcount(i)][i >> 3] |= ((getchar() -  0 ) << ((i & 7) << 2));     getchar();     for (i = 0; i < (1 << n); i++)       b[__builtin_popcount(i)][i >> 3] |= ((getchar() -  0 ) << ((i & 7) << 2));     int j, k;     for (i = 0; i < 32; i++) {       if ((i & 3) < 2) M1 |= (1 << i);       if ((i & 7) < 4) M2 |= (1 << i);       if ((i & 15) < 8) M3 |= (1 << i);       if ((i & 31) < 16) M4 |= (1 << i);       if ((i & 3) == 0) N1 |= (1 << i);       if ((i & 3) == 1) N2 |= (1 << i);     }     for (i = 0; i <= n; i++) zeta(a[i]), zeta(b[i]);     for (i = 0; i <= n; i++) {       memset(c, 0, sizeof(c));       for (j = 0; j <= i; j++) {         for (k = 0; k < (1 << max(n - 3, 0)); k++)           c[k] = add(c[k], mult(a[j][k], b[i - j][k]));       }       for (j = 0; j < (1 << n); j++) {         if (__builtin_popcount(j) & 1) {           if (c[j >> 3] & (1 << ((j & 7) << 2)))             c[j >> 3] ^= (2 << ((j & 7) << 2));         }       }       zeta(c);       for (j = 0; j < (1 << n); j++) {         if (__builtin_popcount(j) & 1) {           if (c[j >> 3] & (1 << ((j & 7) << 2)))             c[j >> 3] ^= (2 << ((j & 7) << 2));         }         if (__builtin_popcount(j) == i)           ans[j >> 3] ^= c[j >> 3] & (3 << ((j & 7) << 2));       }     }     for (i = 0; i < (1 << n); i++)       printf( %d , (ans[i >> 3] >> ((i & 7) << 2)) & 3);     printf(  n );     return 0;   }   