fixed_hash_map.cpp

#include <memory>

inline int32_t murmur_hash_3_finalizer(int32_t key) {
	key ^= key >> 16;
	key *= 0x85ebca6b;
	key ^= key >> 13;
	key *= 0xc2b2ae35;
	key ^= key >> 16;

	return key;
}

class fixed_hash_map {
	struct bucket {
		int32_t key = 0;
		int32_t val = 0;
	};

	const int32_t size;
	std::unique_ptr<bucket[]> buckets;

public:
	fixed_hash_map(const int32_t size) : size{size}, buckets{new bucket[size]} {}

	int32_t get(const int32_t key) const {
		const auto hash = murmur_hash_3_finalizer(key);
		auto idx = hash % size;
		
		while (buckets[idx].key != key && buckets[idx].key != 0) idx = (idx + 1) % size;

		return buckets[idx].val;
	}

	void set(const int32_t key, const int32_t val) {
		const auto hash = murmur_hash_3_finalizer(key);
		auto idx = hash % size;

		while (buckets[idx].key != 0) idx = (idx + 1) % size;

		buckets[idx].key = key;
		buckets[idx].val = val;
	}
};