unordered_set unodered_map api

C++中unordered_set和unordered_map的API示例：

#include <iostream>
#include <unordered_set>
#include <unordered_map>

int main() {
    // unordered_set的API示例
    std::unordered_set<int> mySet;

    // 插入元素
    mySet.insert(10);
    mySet.insert(20);
    mySet.insert(30);

    // 遍历集合
    std::cout << "unordered_set elements:";
    for (auto elem : mySet) {
        std::cout << " " << elem;
    }
    std::cout << std::endl;

    // 检查元素是否存在
    std::cout << "Does mySet contain 20? " << (mySet.count(20) ? "Yes" : "No") << std::endl;

    // 删除元素
    mySet.erase(20);

    // 遍历集合
    std::cout << "unordered_set elements after erasing 20:";
    for (auto elem : mySet) {
        std::cout << " " << elem;
    }
    std::cout << std::endl;

    // 清空集合
    mySet.clear();
    std::cout << "unordered_set size after clearing: " << mySet.size() << std::endl;

    // unordered_map的API示例
    std::unordered_map<int, std::string> myMap;

    // 插入键值对
    myMap[1] = "one";
    myMap[2] = "two";
    myMap[3] = "three";

    // 遍历map
    std::cout << "unordered_map elements:";
    for (const auto& pair : myMap) {
        std::cout << " {" << pair.first << ": " << pair.second << "}";
    }
    std::cout << std::endl;

    // 检查键是否存在
    std::cout << "Does myMap contain key 2? " << (myMap.count(2) ? "Yes" : "No") << std::endl;

    // 删除键值对
    myMap.erase(2);

    // 遍历map
    std::cout << "unordered_map elements after erasing key 2:";
    for (const auto& pair : myMap) {
        std::cout << " {" << pair.first << ": " << pair.second << "}";
    }
    std::cout << std::endl;

    // 清空map
    myMap.clear();
    std::cout << "unordered_map size after clearing: " << myMap.size() << std::endl;

    return 0;
}

插入元素、删除元素、检查元素是否存在、遍历集合以及清空集合。