// time complexity of an unordered_map // using modified hash function #include <bits/stdc++.h> using namespace std; using namespace std::chrono; struct modified_hash { static uint64_t splitmix64(uint64_t x) { x += 0x9e3779b97f4a7c15; x = (x ^ (x >> 30)) * 0xbf58476d1...
>classunordered_map; (1)(since C++11) namespacepmr{ template< classKey, classT, classHash=std::hash<Key>, classKeyEqual=std::equal_to<Key> >usingunordered_map= std::unordered_map<Key, T, Hash, KeyEqual, std::pmr::polymorphic_allocator<std::pair<constKey, T>>>; ...
h> using namespace std; using ll = long long; vector<ll> make_evils(ll prime, ll n) { vector<ll> ret(n); for (ll i = 0; i < n; i++) ret[i] = (i + 1) * prime; return ret; } unordered_set<ll> st; void test_evils(const vector<ll>& evils) { st = unordered_...
比较map、hash_map和unordered_map的执行效率以及内存占用情况 **/#include<sys/types.h>#include<unistd.h>#include<sys/time.h>#include<iostream>#include<fstream>#include<string>#include<map>#include<ext/hash_map>#include<tr1/unordered_map>usingnamespacestd;usingnamespace__gnu_cxx;usingnamespacestd...
#include <iostream> #include <unordered_map> using namespace std; int main(void) { unordered_map<char, int> um1 = { {'a', 1}, {'b', 2}, {'c', 3}, {'d', 4}, {'e', 5} }; unordered_map<char, int>um2(move(um1)); cout << "Unordered_map contains following elements"...
**/#include<sys/types.h>#include<unistd.h>#include<sys/time.h>#include<iostream>#include<fstream>#include<string>#include<map>#include<ext/hash_map>#include<tr1/unordered_map>usingnamespacestd;usingnamespace__gnu_cxx;usingnamespacestd::tr1;#defineN 100000000//分别测试N=100,000、N=1,000...
Let us compile and run the above program, this will produce the following result − Unordered map contains following elements before erase operation e = 5 a = 1 b = 2 c = 3 d = 4 Unordered map contains following elements after erase operation a = 1 b = 2 c = 3 d = 4 ...
Complexity 1-3)Same as foremplace. 4-6)Same as foremplace_hint. Unlikeinsertoremplace, these functions do not move from rvalue arguments if the insertion does not happen, which makes it easy to manipulate maps whose values are move-only types, such asstd::unordered_map<std::string,std:...
This is not a bug report, more of an interesting data point. In the past week I've been trying out absl::flat_hash_map and google::dense_hash_map (and sets) and comparing performance to STL counterparts. The following gist contains bench...
#include <iostream> #include <unordered_map> using namespace std; int main(void) { unordered_map<char, int> um = { {'a', 1}, {'b', 2}, {'c', 3}, }; um.insert(pair<char, int>('d', 4)); um.insert(pair<char, int>('e', 5)); cout << "Unordered map contains follo...