I have a c++ map declared as follows
std::map<std::string, int> wordMap= {
{ "is", 6 },
{ "the", 5 },
{ "hat", 9 },
{ "at", 6 }
};
I would like to know how to find the number of distinct values of int existing in wordMap.
In this example, I would expect an output of 3 as i have 3 different distinct values (6,5,9).
Try to use std::set for counting:
std::set<int> st;
for (const auto &e : wordMap)
st.insert(e.second);
std::cout << st.size() << std::endl;
One way is to store all keys of wordMap in a set and then query its size:
#include <unordered_set>
#include <algorithm>
std::map<std::string, int> wordMap= { /* ... */ };
std::unordered_set<int> values;
std::transform(wordMap.cbegin(), wordMap.cend(), std::insert_iterator(values, keys.end()),
[](const auto& pair){ return pair.second; });
const std::size_t nDistinctValues = values.size();
Note that in C++20, the above presumably boils down to
#include <ranges>
#include <unordered_set>
const std::unordered_set<int> values = wordMap | std::ranges::values_view;
const std::size_t nDistinctValues = values.size();
