max_element() Function in C++

This C++ program demonstrates the max_element algorithm on a container. The max_element() function has two overloaded forms – one with a compare predicate as the third parameter and another without it. The program demonstrates both of the overloaded forms where one prints the element with maximum value in a vector and another using a compare function to find the pair element with maximum value in a map. The compare function compares the two pairs on the basis of their second arguments.

Here is the source code of the C++ program which demonstrates the max_element algorithm on a container. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C++ Program to demonstrate the max_element() algorithm on a container

```
 */
```
```
#include <iostream>
```
```
#include <algorithm>
```
```
#include <vector>
```
```
#include <map>
```
```
#include <string>
```
```
 
```

bool compare(std::pair <std::string, int> p, std::pair <std::string, int> q )

```
{
```
```
    return p.second < q.second;
```
```
}
```
```
 
```
```
void print(const std::vector <int>& v)
```
```
{
```

    std::vector <int>::const_iterator i;

    for(i = v.begin(); i != v.end(); i++)

```
    {
```
```
        std::cout << *i << " ";
```
```
    }
```
```
    std::cout << std::endl;
```
```
}
```
```
 
```

void fun(std::pair <std::string, int> p)

```
{
```

    std::cout << p.first << "\t" << p.second << std::endl;

```
}
```
```
 
```
```
int main()
```
```
{
```

    int arr[] = {10, 20, 30, 50, 40, 100, 70, 60, 80, 90};

    std::vector <int> v(arr, arr + sizeof(arr)/sizeof(int));

```
    std::map <std::string, int> marks;
```
```
    std::pair <std::string, int> max;
```
```
    marks["Alice"] = 60;
```
```
    marks["Annie"] = 99;
```
```
    marks["Harry"] = 90;
```
```
    marks["Garry"] = 80;
```
```
 
```

    std::cout << "max_element() without predicate " << std::endl;

```
    std::cout << "Vector : ";
```
```
    print(v);
```
```
    std::cout << "Maximum element = "
```

              << *std::max_element(v.begin(), v.end())

```
              << std::endl;
```

    std::cout << "\nmax_element() with predicate" << std::endl;

    std::cout << "Name\tMarks" << std::endl;

    for_each(marks.begin(), marks.end(), fun);

    max = (*std::max_element(marks.begin(), marks.end(), compare));

    std::cout << "Person with maximum marks = " << max.first

              << ", Marks = " << max.second << std::endl;

```
}
```

$ a.out
max_element() without predicate 
Vector : 10 20 30 50 40 100 70 60 80 90 
Maximum element = 100
 
max_element() with predicate
Name    Marks
Alice   60
Annie   99
Garry   80
Harry   90
Person with maximum marks = Annie, Marks = 99

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