Finding the max value in a map

Question

I've been doing a basic program to find the max, min, median, variance, mode etc. of a vector. Everything went fine until I got to the mode.

The way I see it, I should be able to loop through the vector, and for each number that occurs I increment a key on the map. Finding the key with the highest value would then be the one that occurred the most. Comparing to other keys would tell me if it's a single multiple or no mode answer.

Here's the chunk of code that's been causing me so much trouble.

map<int,unsigned> frequencyCount; // This is my attempt to increment the values // of the map everytime one of the same numebers  for(size_t i = 0; i < v.size(); ++i)     frequencyCount[v[i]]++;  unsigned currentMax = 0; unsigned checked = 0; unsigned maax = 0; for(auto it = frequencyCount.cbegin(); it != frequencyCount.cend(); ++it )     //checked = it->second;     if (it ->second > currentMax)     {         maax = it->first;     }     //if(it ->second > currentMax){     //v = it->first  cout << " The highest value within the map is: " << maax << endl; 

The entire program can be seen here. http://pastebin.com/MzPENmHp

Answer 1

You can use std::max_element to find the highest map value (the following code requires C++11):

std::map<int, size_t> frequencyCount; using pair_type = decltype(frequencyCount)::value_type;  for (auto i : v)     frequencyCount[i]++;  auto pr = std::max_element (     std::begin(frequencyCount), std::end(frequencyCount),     [] (const pair_type & p1, const pair_type & p2) {         return p1.second < p2.second;     } ); std::cout << "A mode of the vector: " << pr->first << '\n';