Find element with the maximum value in a map in C++

This post will discuss how to find an element with the maximum value in a map in C++.

1. Using `std::max_element`

The recommended solution is to use the std::max_element to find an element having the maximum value in a map. It returns an iterator pointing to an element with the maximum value in the specified range. It is defined in the <algorithm> header.

#include <iostream>

#include <map>

#include <algorithm>

int main()

{

std::map<std::string, int> map = {

{"two", 2}, {"one", 1}, {"four", 4}, {"three", 3}

};

auto pr = std::max_element(map.begin(), map.end(), [](const auto &x, const auto &y) {

return x.second < y.second;

});

std::cout << pr->first << std::endl; // four

return 0;

}

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Here’s a generic version using templates.

#include <iostream>

#include <map>

#include <algorithm>

template<typename K, typename V>

std::pair<K,V> getMaximumValue(const std::map<K,V> &map) {

return *std::max_element(map.begin(), map.end(), [](std::pair<K,V> const &x, std::pair<K,V> const &y) {

return x.second < y.second;

});

}

int main()

{

std::map<std::string, int> map = {

{"two", 2}, {"one", 1}, {"four", 4}, {"three", 3}

};

std::pair<std::string, int> pair = getMaximumValue(map);

std::cout << pair.first << std::endl; // four

return 0;

}

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2. Using Loop

Alternatively, we can write a custom function for finding an element with the maximum value in the map. It can be implemented as follows in C++.

#include <iostream>

#include <map>

#include <climits>

int main()

{

std::map<std::string, int> map = {

{"two", 2}, {"one", 1}, {"four", 4}, {"three", 3}

};

std::pair<std::string, int> maxValuePair;

int maxValue = INT_MIN;

for (const auto &entry: map)

{

if (maxValue < entry.second)

{

maxValue = entry.second;

maxValuePair = entry;

}

std::cout << maxValuePair.first << std::endl; // four

return 0;

}

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That’s all about finding the element with the maximum value in a map in C++.

Find element with the maximum value in a map in C++

1. Using std::max_element

2. Using Loop

1. Using `std::max_element`