C++ Algorithm Library - is_permutation() Function

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Description

The C++ function std::algorithm::is_permutation() tests whether a sequence is permutation of other or not. It uses operator == for comparison.

Declaration

Following is the declaration for std::algorithm::is_permutation() function form std::algorithm header.

C++11

template <class ForwardIterator1, class ForwardIterator2>
bool is_permutation(ForwardIterator1 first1,ForwardIterator1 last1,
   ForwardIterator2 first2);

Parameters

• first1 − Input iterator to the initial position of the first sequence.

• last1 − Input iterator to the final position of the first sequence.

• first2 − Input iterator to the initial position of the second sequence.

Return value

Returns true if first range is permutation of another otherwise it returns false.

Exceptions

Throws exception if either the element comparison or an operation on an iterator throws exception.

Please note that invalid parameters cause undefined behavior.

Time complexity

Quadratic.

Example

The following example shows the usage of std::algorithm::is_permutation() function.

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

using namespace std;

int main(void) {
   vector<int> v1 = {1, 2, 3, 4, 5};
   vector<int> v2 = {5, 4, 3, 2, 1};
   bool result;

   result = is_permutation(v1.begin(), v1.end(), v2.begin());

   if (result == true)
      cout << "Both vector contains same elements." << endl;

   v2[0] = 10;

   result = is_permutation(v1.begin(), v1.end(), v2.begin());

   if (result == false)
      cout << "Both vector doesn't contain same elements." << endl;
   return 0;
}

Let us compile and run the above program, this will produce the following result −

Both vector contains same elements.
Both vector doesn't contain same elements.