#include <vector>
    #include <iostream>
    #include <algorithm>
    int main()
    {
      std::vector<std::pair<int, int>> v = {{1,2}, {3,4}, {5,6}};
      auto p = std::make_pair(3, 4);
     
      if(std::find(v.begin(), v.end(), p) != v.end())
          std::cout << "yes\n";
    }

    #include <vector>
    #include <cassert>
    #include <iostream>
    #include <algorithm>
    int main()
    {
      std::vector<std::pair<int, int>> v = {{1,2}, {3,4}, {5,6}};
      auto p = std::make_pair(3, 4);
     
      assert(std::is_sorted(v.begin(), v.end()));
     
      if(std::binary_search(v.begin(), v.end(), p))
          std::cout << "yes\n";
    }

#include <map>
#include <string>
#include <iterator>
 
std::map<std::string, int>::iterator serachByValue(std::map<std::string, int> & mapOfWords, int val)
{
    // Iterate through all elements in std::map and search for the passed element
    std::map<std::string, int>::iterator it = mapOfWords.begin();
    while(it != mapOfWords.end())
    {
        if(it->second == val)
        return it;
        it++;
    }
}
int main()
{
    std::map<std::string, int> mapOfWords;
    // Inserting data in std::map
    mapOfWords.insert(std::make_pair("earth", 1));
    mapOfWords.insert(std::make_pair("moon", 2));
    mapOfWords["sun"] = 3;
 
    std::map<std::string, int>::iterator it = serachByValue(mapOfWords, 3);
    if(it != mapOfWords.end())
        std::cout<<it->first<<" :: "<<it->second<<std::endl;
 
return 0;
}

struct WordGreaterComparator
{
    bool operator()(const std::string & left, const std::string & right) const
    {
        return (left > right);
    }
};

std::map<std::string, int, WordGreaterComparator > mapOfWords_2;
mapOfWords_2.insert(std::make_pair("earth", 1));
mapOfWords_2.insert(std::make_pair("moon", 2));
mapOfWords_2.insert(std::make_pair("sun", 3));
for(std::map<std::string, int>::iterator it = mapOfWords_2.begin(); it != mapOfWords_2.end(); it++)
   std::cout<<it->first<<" :: "<<it->second<<std::endl;

Output:

sun :: 3
moon :: 2
earth :: 1