安全的哈希
代码如下
const int maxn = 2e5 + 5;
struct custom_hash
{static uint64_t splitmix64(uint64_t x) {x ^= x << 13;x ^= x >> 7;x ^= x << 17;return x; }size_t operator () (uint64_t x) const {static const uint64_t FIXED_RANDOM = std::chrono::steady_clock::now().time_since_epoch().count(); // 时间戳return splitmix64(x + FIXED_RANDOM);}
};
std::unordered_map<uint64_t, int, custom_hash> mp;