unordered_map & unordered_multimap
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#include<iostream>
#include<unordered_map>
#include<string>
#include<iterator>
using namespace std;
int main()
{
pair<int,string> arr[5]={
pair<int,string>(1,"北京"),
pair<int,string>(2,"上海"),
pair<int,string>(2,"昆明"),
pair<int,string>(4,"重庆"),
pair<int,string>(3,"天津")
};
unordered_map<int ,string> test1(arr,arr+5);
unordered_map<int ,string>::iterator it = test1.begin();
for(;it!=test1.end();++it)
{
cout<<it->first<<" "<<it->second<<endl;
}
//无序map,不能使用less<>和greater<>来排序了
cout<<"test unordered_multimap:"<<endl;
unordered_multimap<int ,string> test2(arr,arr+5);
for(auto& elem:test2)
{
cout<<elem.first<<" "<<elem.second<<endl;
}
cout<<"test random access:"<<endl;
cout<<test1[1]<<endl; // unordered_multimap不支持随机访问
unordered_multimap<int,string>::iterator umit = test2.find(2);
cout<<umit->first<<" "<<umit->second<<endl;
}
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unordered_set & unordered_multiset
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#include<iostream>
#include<unordered_set>
using namespace std;
int main()
{
int arr[7] = {2,2,1,3,4,5,3};
unordered_set<int> test1(arr,arr+7);
for(auto& elem:test1)
cout<<elem<<" ";
cout<<endl;
cout<<"test unordered_multiset"<<endl;
unordered_multiset<int> test2(arr,arr+7);
for(auto& elem:test2)
cout<<elem<<" ";
cout<<endl;
unordered_multiset<int> test3(arr,arr+7);
cout<<"test random access"<<endl;
cout<<*(test2.find(3))<<endl;
cout<<*(test2.find(2))<<endl;
cout<<"value = 2 cnt:"<<test2.count(2)<<endl;
return 0;
}
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