How to hash a tri-state two-dimensional array?

Question

Consider the following code. What is a good hashing function for the array in Key to be used in an unordered_map? #include using namespace std; enum TriState { S0 = -1, S1 = 0, S2 = +1 }; struct K { // Key for the map TriState a[8][8]; bool operator==(const K& k1) const { for (int i = 0; i < 64; i++) if (k1.a[0][i] != a[0][i]) return false; return true; } }; struct Hash { size_t operator()(const K& k) const { size_t s; // s = what is a good hash value? return s; } }; unordered_map m; JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

This algorithm should be fast and provide near-uniform hashing: size_t s = 0x3a7eb429; // Just some random seed value for (int i = 0; i != 8; ++i) { for (int j = 0; j != 8; ++j) { s = (s >> 1) | (s << (sizeof(size_t) * 8 - 1)); s ^= k.a[i][j] * 0xee6b2807; } } s *= 0xee6b2807; s ^= s >> 16; After that, if you want to make the hashing even stronger, hash s another time using for example MurmurHash3.