Головоломка Хитори

#include <iostream>
using namespace std;
typedef const unsigned long long int cull;
typedef const int cint;
 
cull fill(cint i, cull a, cull b), solve(cull a);
 
cint w=8, h=8, po=100; cull msk = ~(~cull(0)>>h*w<<h*w);
cint f[h][w] = {
    {2,8,1,2,3,8,7,5},{7,8,6,3,3,2,5,1},{5,1,4,8,2,1,3,7},{8,4,2,8,6,5,6,3},
    {1,7,1,5,8,4,3,3},{4,1,7,8,5,8,8,2},{3,1,8,4,6,7,5,5},{5,5,1,1,3,6,4,3}};
//cint f[h][w] = {
//    {1,5,6,1,7,7,2},{1,4,6,3,2,6,5},{2,2,3,1,5,5,3},{7,7,1,1,5,2,3},
//    {6,1,2,7,7,4,4},{3,3,2,2,1,7,4},{4,6,7,1,3,1,4}};
//cint f[h][w] = {{5,3,3,2,1},{2,2,4,1,1},{1,3,2,4,3},{2,4,4,3,3},{1,1,3,5,2}};
 
const bool ib(cint i, cull a) {return (a>>i)&1;}
 
cull fill_r(cint i, cull a, cull b) {return ib(i,a) && !ib(i,b) ? b | fill(i,a,b) : b;}
 
cull fill  (cint i, cull a, cull b) {
    cint r=i/w, c=i%w; cull bc = b | cull(1)<<i;
    cull bl = c>0 ?   fill_r(i-1, a, bc) : bc;
    cull br = c<w-1 ? fill_r(i+1, a, bl) : bl;
    cull bu = r>0 ?   fill_r((r-1)*w+c, a, br) : br;
    return    r<h-1 ? fill_r((r+1)*w+c, a, bu) : bu;
}
cint fnd_1(cint i, cull a) {return ib(i,a) ? i : fnd_1(i+1,a);}
 
const bool fill_inv(cull a) {cull b = msk & ~a; return b == fill(fnd_1(0,b), b, 0);}
 
 
cull fnd_e(cint j, cint i, cint d, cull a, cint e, cull r) {
    return j ? fnd_e(j-1, i+d, d, a, e, !ib(i,a) && e==f[i/w][i%w] ? r*po+i+1 : r) : r;}
    
cull mul_ind(cint j, cint i, cint d, cull a) {
    if (j) {cull r = fnd_e(j, i, d, a, f[i/w][i%w], 0);
            return r>po ? r : mul_ind(j-1, i+d, d, a);}
    else return 0;}
                
cull s_r(cint r, cull a) {
    if (r>=h) return 0; else {cull s = mul_ind(w,r*w,1,a); return s ? s : s_r(r+1,a);}}
 
cull s_c(cint c, cull a) {
    if (c>=w) return 0; else {cull s = mul_ind(h,c,  w,a); return s ? s : s_c(c+1,a);}}
 
cull steps(cull a) {cint s=s_r(0,a); return s ? s : s_c(0,a);}
 
 
cull makestep(cint i, cull ain) {
    cint r=i/w, c=i%w; cull a = ain | cull(1)<<i;   
    return (c>0 && ib(i-1,a)) || (c<w-1 && ib(i+1,a)) || (r>0 && ib((r-1)*w+c,a))
        || (r<h-1 && ib((r+1)*w+c,a)) || !fill_inv(a) ? 0 : a;}
 
cull try_steps(cull s, cull a) {
    if (s) {cull b = makestep(s%po-1, a);
            cull c = b ? solve(b) : 0;
            return c ? c : try_steps(s/po, a);} else return 0;}
 
cull solve(cull a) {cull s=steps(a); return s ? try_steps(s,a) : a;}
 
void show(cint i, cull a) {
    if (i%w==0) cout<<'\n';
    if (i<h*w) {cout<<(a&1 ? "[" : " ")<<f[i/w][i%w]<<(a&1 ? "]" : " ")<<'\t';
                show(i+1,a>>1);} else cout<<'\n';}
 
int main() {show(0, solve(0));}