Finding max element in a list, but handle duplicates?

Question

Suppose I have a vector/list of integers. What is the best way to get another list which contains the max number in that list, but include the duplicates?

For example:

max([1, 2, 3, 3, -6]) -> [3, 3]
max([1, 3, 1]) -> [3]

This is my code:

std::vector<int> max(std::vector<int>& vec) {
std::vector<int> result;
int max = vec[0];
for (auto& v : vec) {
if (v > max) {
result.clear();
result.push_back(v);
max = v;
} else if (v == max) {
result.push_back(v);
}
}
return result;
}

Basically I'm going over the vector, checking if the current value is bigger than max, and if it is, I reset the result vector, push the new value and set the new max. If it is the same as the current max, i push back the current value.

Is this the best way to do it? I'm sure there are other ways...

P.S my actual code doesn't work with a vector as the input but with an unordered map, doesn't matter though

Answer 1

To find the max element...I'd be using max_element from the <algorithm> header file...(just remember to de-reference it as you assign in to a variable)...then just loop through your vector as you've done, compare and push_back as necessary.

Answer 2

Working example based on rodwynnejones suggestion.

https://code.sololearn.com/cloUG6IZ257U/?ref=app

Answer 3

Flash looks alright but as I mentioned I can't sort the values because I'm using an std::unordered_map. I got my code working and a little better though, so thanks for your contribution.

Answer 4

inxanedev! not that elegant

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>

std::vector<int>& m(std::vector<int>& in, std::vector<int>& out)
{
std::sort(in.begin(), in.end(), std::greater<>());
int e = in.at(0);
for (int& i : in)
{
if (i == e)
{
out.push_back(i);
}
else
{
break;
}
}
return out;
}

std::ostream& operator<<(std::ostream& os, std::vector<int>& v)
{
for (auto& i : v)
{
os << i << ' ';
}
os << '\n';
return os;
}

int main()
{
std::vector<int> in{ 2,1,4,5,4,4,5,3,5,4};
std::vector<int> out{};
std::cout << m(in, out);
return 0;
}

https://code.sololearn.com/cULtnX1t8xrM/?ref=app