Internally, the elements in the unordered_set are not sorted in any particular order, but organized into buckets depending on their hash values to allow for fast access to individual elements directly by their values (with a constant average time complexity on average). unordered_set containers ar...
std::unordered_setis an associative container that contains a set of unique objects of typeKey. Search, insertion, and removal have average constant-time complexity. Internally, the elements are not sorted in any particular order, but organized into buckets. Which bucket an element is placed into...
unordered_set 只包含键,没有值。没有从键到值的映射,因此不需要 operator[]。 unordered_map 将键映射到值。 您可以使用 --- 中的各种 find unordered_set 来定位事物。 原文由 1201ProgramAlarm 发布,翻译遵循 CC BY-SA 3.0 许可协议 回复 撰写回答 你尚未登录,登录后可以 和开发者交流问题的细节 关注...
Also wondering why the unordered_set is about 2'500 times slower for a find than a vector? I mean the worst case scenario for vector is supposed to be O(n), isn't unordered_set supposed to be better than that? I know that trying to predict what is the average complexity is usually...
unordered_set::emplace_hint Lookup unordered_set::count unordered_set::find unordered_set::contains (C++20) unordered_set::equal_range Bucket interface unordered_set::begin(size_type)unordered_set::cbegin(size_type) unordered_set::end(size_type)unordered_set::cend(size_type) unordered_set::buc...
在C++中,可以使用std::pair作为哈希表(在C++中通常指的是std::unordered_map或std::unordered_set)的键值。然而,要确保键值可以被哈希化(也就是要为这个键值类型提供一个哈希函数)并且能够被比较(也就是要为这个键值类型提供一个等于运算符)。 关于不能作为键值的类型,那些没有默认的哈希函数或者无法用==运算符...
unordered_map are not sorted in any particular order with respect to either their key or mapped values, but organized into buckets(桶) depending on their hash values to allow for fast access to individual elements directly by their key values (with a constant average time complexity on average...
// unordered_set::begin/end example#include <iostream>#include <string>#include <unordered_set>intmain () { std::unordered_set<std::string> myset = {"Mercury","Venus","Earth","Mars","Jupiter","Saturn","Uranus","Neptune"}; std::cout <<"myset contains:";for(autoit = myset.begin...
// swap (unordered_multiset specialization)#include <iostream>#include <string>#include <unordered_set>intmain () { std::unordered_multiset<std::string> first = {"cow","chicken","pig","pig"}, second = {"wolf","rabbit","rabbit"}; swap(first,second); std::cout <<"first:";for(cons...
find() does not modify the map. It returns an iterator. If the key does not exist, it will return map.end(). Example: 1 2 3 4 5 6 7 std::map<int,int>myMap;autoit=myMap.find(10);if(it==myMap.end()){std::cout<<"Key not found!"<<std::endl;}else{std::cout<<"Value:...