How to Find the Maximum Element of a Vector using STL in C++?

Given a vector, find the maximum element of the vector using STL in C++.

Example

Input: v = {2, 4, 1, 5, 3}
Output: 5
Explanation: 5 is the largest element of vector.

Input: v = {11, 23, 3, 5, 24}
Output: 24
Explanation: 24 is the largest element of the given range.

STL provides the following different methods to find the maximum element in the vector in C++.

Using std::max_element()

The simplest way to find the maximum element in the vector is by using the std::max_element(). This function returns the iterator to the maximum element in the given range of elements.

Syntax

std::max_element(v.begin(), v.end());

where, v is the vector.

Example

// C++ program to find maximum element
// in vector using std::max_element()
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v = {2, 4, 1, 5, 3};

    // Finding the maximum element in vector
    // using std::max_element()
    cout << *max_element(v.begin(), v.end());
    return 0;
}

5

Time Complexity: O(n), where n is the number of elements in the vector.
Auxiliary Space: O(1)

Using std::minmax_element()

The std::minmax_element() function can be used to find the maximum and the minimum element in the STL container at once. It returns a pair in which pair::first is minimum, and pair::second is maximum.

Syntax

std::minmax_element(v.begin(), v.end());

where, v is the vector.

Example

// C++ Program to find maximum element in vector
// using std::minmax_element()
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v = {2, 4, 1, 5, 3};

    // Finding both minimum and maximum elements
    auto p = minmax_element(v.begin(), v.end());

    // Printing the maximum element
    cout << *p.second;
    return 0;
}

5

Time Complexity: O(n), where n is the number of elements in the vector.
Auxiliary Space: O(1)

Using Priority Queue

We can also find the maximum element in a vector by copying all elements of vector into std::priority_queue as it implements the max heap in which the maximum element will always be at the top. This method is useful when we want to find the maximum element between frequent insertions and deletions.

Example

// C++ program to find maximum element in
// vector using priority_queue
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v = {2, 4, 1, 5, 3};

    // Copying all elements of vector v into
    // priority queue
    priority_queue<int> pq(v.begin(), v.end());

    // Fetching the top element which is the
    // maximum element of vector
    cout << pq.top();
    return 0;
}

5

Time Complexity: O(n), where n is the number of elements in the vector.
Auxiliary Space: O(n)

Using std::sort()

In a vector sorted in ascending order, the maximum element is at end of the vector. So, we sort vector using std::sort() function and find the maximum element.

Example

// C++ Program to find maximum element
// of a vector by sorting
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v = {2, 4, 1, 5, 3};

    // Sort the vector in ascending order
    sort(v.begin(), v.end());

    // maximum element at the end 
    cout << v.back();
    return 0;
}

5

Time Complexity: O(n * log n), where n is the number of elements in the vector.
Auxiliary Space: O(log n)