unordered_multiset bucket_size() function in C++ STL

The unordered_multiset::bucket_size() is a built-in function in C++ STL which returns the number of elements in the bucket which has the element val. It will always be lower than the bucket_count. The number of elements in a bucket influences the time it takes to access a particular element in the bucket

Syntax:

unordered_multiset_name.bucket_size(val)

Parameters: The function accepts a parameter val which specifies the element whose size of the bucket is to be returned.

Return Value: It returns an unsigned integral type which denotes the number of elements in the bucket which has the element val.

Below programs illustrate the above function:

Program 1:

// C++ program to illustrate the
// unordered_multiset::bucket_size() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration
    unordered_multiset<int> sample;

    // inserts element
    sample.insert(11);
    sample.insert(11);
    sample.insert(11);
    sample.insert(12);
    sample.insert(13);
    sample.insert(13);
    sample.insert(14);

    for (auto it = sample.begin(); it != sample.end(); it++) {
        cout << "The bucket size in which " << *it
             << " is " << sample.bucket_size(*it) << endl;
    }
    return 0;
}

Output:

The bucket size in which 14 is 1
The bucket size in which 11 is 3
The bucket size in which 11 is 3
The bucket size in which 11 is 3
The bucket size in which 12 is 1
The bucket size in which 13 is 2
The bucket size in which 13 is 2

Program 2:

// C++ program to illustrate the
// unordered_multiset::bucket_size() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration
    unordered_multiset<int> sample;

    // inserts element
    sample.insert(1);
    sample.insert(1);
    sample.insert(1);
    sample.insert(2);
    sample.insert(3);
    sample.insert(4);
    sample.insert(3);

    for (auto it = sample.begin(); it != sample.end(); it++) {
        cout << "The bucket size in which " << *it
             << " is " << sample.bucket_size(*it) << endl;
    }
    return 0;
}

Output:

The bucket size in which 1 is 3
The bucket size in which 1 is 3
The bucket size in which 1 is 3
The bucket size in which 2 is 1
The bucket size in which 3 is 2
The bucket size in which 3 is 2
The bucket size in which 4 is 1