スパコンで約2時間36分かかったという、5×5の魔方陣の全解列挙を、パソコンで試す（C++）http://blog.unfindable.net/archives/7179
| #include <iostream> | |
| #include <fstream> | |
| #include <sstream> | |
| #include <algorithm> | |
| #include <ctime> | |
| #include <omp.h> | |
| using namespace std; | |
| const char* outputfile = "result"; | |
| int main() | |
| { | |
| clock_t start = clock(); | |
| const int B = 5; | |
| const int N = 25; | |
| const int S = 65; | |
| const int mask = (1 << B) - 1; | |
| int threads = omp_get_max_threads(); | |
| cout << "num of threads: " << threads << endl; | |
| int* counts = new int[threads]; | |
| ofstream** files = new ofstream*[threads]; | |
| for (int t = 0; t < threads; ++t){ | |
| counts[t] = 0; | |
| stringstream ss; | |
| ss << outputfile << t; | |
| files[t] = new ofstream(ss.str().c_str(), ios_base::binary); | |
| } | |
| #pragma omp parallel | |
| #pragma omp for schedule(dynamic, 1024) | |
| for (int i = 0; i < (1 << 25); ++i) { | |
| if ((i % (1 << 20)) == 0) cout << (i / (1 << 20)) << "/32" << endl; | |
| const int x7 = ((i >> (B * 0)) & mask) + 1; | |
| if (x7 > N - 3) continue; | |
| const int x9 = x7 + ((i >> (B * 1)) & mask) + 1; | |
| if (x9 > N) continue; | |
| const int x17 = x9 + ((i >> (B * 2)) & mask) + 1; | |
| if (x17 > N) continue; | |
| int used = (1 << x7) + (1 << x9) + (1 << x17); | |
| const int x19 = x7 + ((i >> (B * 3)) & mask) + 1; | |
| if (x19 > N || (used & (1 << x19))) continue; | |
| used ^= (1 << x19); | |
| const int x13 = ((i >> (B * 4)) & mask) + 1; | |
| if (x13 > N || (used & (1 << x13))) continue; | |
| used ^= (1 << x13); | |
| for (int x1 = max(1, S - x7 - x13 - x19 - N); x1 <= min(N, S - x7 - x13 - x19 - 1); ++x1) { | |
| if (!(used & (1 << x1))) { | |
| used ^= (1 << x1); | |
| const int x25 = S - x1 - x7 - x13 - x19; | |
| if (!(used & (1 << x25))) { | |
| used ^= (1 << x25); | |
| for (int x5 = max(1, S - x9 - x13 - x17 - N); x5 <= min(N, S - x9 - x13 - x17 - 1); ++x5) { | |
| if (!(used & (1 << x5))) { | |
| used ^= (1 << x5); | |
| const int x21 = S - x5 - x9 - x13 - x17; | |
| if (!(used & (1 << x21))) { | |
| used ^= (1 << x21); | |
| for (int x2 = max(1, max(S - x1 - x5, S - x7 - x17) - 49); x2 <= min(N, min(S - x1 - x5, S - x7 - x17) - 3); ++x2) { | |
| if (!(used & (1 << x2))) { | |
| used ^= (1 << x2); | |
| for (int x3 = max(1, S - x1 - x2 - x5 - N); x3 <= min(N, S - x1 - x2 - x5 - 1); ++x3) { | |
| if (!(used & (1 << x3))) { | |
| used ^= (1 << x3); | |
| const int x4 = S - x1 - x2 - x3 - x5; | |
| if (!(used & (1 << x4))) { | |
| used ^= (1 << x4); | |
| for (int x12 = max(1, S - x2 - x7 - x17 - N); x12 <= min(N, S - x2 - x7 - x17 - 1); ++x12) { | |
| if (!(used & (1 << x12))) { | |
| used ^= (1 << x12); | |
| const int x22 = S - x2 - x7 - x12 - x17; | |
| if (!(used & (1 << x22))) { | |
| used ^= (1 << x22); | |
| for (int x24 = max(1, max(S - x4 - x9 - x19, S - x21 - x22 - x25) - N); x24 <= min(N, min(S - x4 - x9 - x19, S - x21 - x22 - x25) - 1); ++x24) { | |
| if (!(used & (1 << x24))) { | |
| used ^= (1 << x24); | |
| const int x14 = S - x4 - x9 - x19 - x24; | |
| if (1 <= x14 && x14 <= N && !(used & (1 << x14))) { | |
| used ^= (1 << x14); | |
| const int x23 = S - x21 - x22 - x24 - x25; | |
| if (1 <= x23 && x23 <= N && !(used & (1 << x23))) { | |
| used ^= (1 << x23); | |
| for (int x8 = max(1, S - x3 - x13 - x23 - N); x8 <= min(N, S - x3 - x13 - x23 - 1); ++x8) { | |
| if (!(used & (1 << x8))) { | |
| used ^= (1 << x8); | |
| const int x18 = S - x3 - x8 - x13 - x23; | |
| if (!(used & (1 << x18))) { | |
| used ^= (1 << x18); | |
| for (int x6 = max(1, S - x7 - x8 - x9 - N); x6 <= min(N, S - x7 - x8 - x9 - 1); ++x6) { | |
| if (!(used & (1 << x6))) { | |
| used ^= (1 << x6); | |
| const int x10 = S - x6 - x7 - x8 - x9; | |
| if (!(used & (1 << x10))) { | |
| used ^= (1 << x10); | |
| for (int x11 = max(1, max(S - x1 - x6 - x21, S - x12 - x13 - x14) - N); x11 <= min(N, min(S - x1 - x6 - x21, S - x12 - x13 - x14) - 1); ++x11) { | |
| if (!(used & (1 << x11))) { | |
| used ^= (1 << x11); | |
| const int x15 = S - x11 - x12 - x13 - x14; | |
| if (1 <= x15 && x15 <= N && !(used & (1 << x15))) { | |
| used ^= (1 << x15); | |
| const int x16 = S - x1 - x6 - x11 - x21; | |
| if (1 <= x16 && x16 <= N && !(used & (1 << x16))) { | |
| used ^= (1 << x16); | |
| const int x20 = S - x5 - x10 - x15 - x25; | |
| if (S == x16 + x17 + x18 + x19 + x20 && 1 <= x20 && x20 <= N && !(used & (1 << x20))) { | |
| int t = omp_get_thread_num(); | |
| ++counts[t]; | |
| *files[t] << (char)x1 << (char)x2 << (char)x3 << (char)x4 << (char)x5 << (char)x6 << (char)x7 << (char)x8 << (char)x9 << (char)x10 << (char)x11 << (char)x12 << (char)x13 << (char)x14 << (char)x15 << (char)x16 << (char)x17 << (char)x18 << (char)x19 << (char)x20 << (char)x21 << (char)x22 << (char)x23 << (char)x24 << (char)x25; | |
| } | |
| used ^= (1 << x16); | |
| } | |
| used ^= (1 << x15); | |
| } | |
| used ^= (1 << x11); | |
| } | |
| } | |
| used ^= (1 << x10); | |
| } | |
| used ^= (1 << x6); | |
| } | |
| } | |
| used ^= (1 << x18); | |
| } | |
| used ^= (1 << x8); | |
| } | |
| } | |
| used ^= (1 << x23); | |
| } | |
| used ^= (1 << x14); | |
| } | |
| used ^= (1 << x24); | |
| } | |
| } | |
| used ^= (1 << x22); | |
| } | |
| used ^= (1 << x12); | |
| } | |
| } | |
| used ^= (1 << x4); | |
| } | |
| used ^= (1 << x3); | |
| } | |
| } | |
| used ^= (1 << x2); | |
| } | |
| } | |
| used ^= (1 << x21); | |
| } | |
| used ^= (1 << x5); | |
| } | |
| } | |
| used ^= (1 << x25); | |
| } | |
| used ^= (1 << x1); | |
| } | |
| } | |
| } | |
| int sum = 0; | |
| for (int t = 0; t < threads; ++t) { | |
| sum += counts[t]; | |
| files[t]->close(); | |
| } | |
| cout << "num of solution: " << sum << endl; | |
| clock_t now = clock(); | |
| double duration = double(now - start) / CLOCKS_PER_SEC; | |
| cout << "time for count: " << duration << " sec." << endl; | |
| return 0; | |
| } |
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