forward_list::unique() is an inbuilt function in C++ STL which removes all consecutive duplicate elements from the forward_list. It uses binary predicate for comparison.
Syntax:
forwardlist_name.unique(BinaryPredicate name)
Parameters: The function accepts a single parameter which is a binary predicate that returns true if the elements should be treated as equal.
It has following syntax:
bool name(data_type a, data_type a)
Return value: The function does not return anything.
CPP
// C++ program to illustrate the // unique() function #include <bits/stdc++.h> using namespace std;
// Function for binary_predicate /*bool compare(int a, int b) { return (abs(a) == abs(b));
} // This function can also be used and passed inside // unique(), to get the same result */ int main()
{ forward_list< int > list = { 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 2, 4, 4 };
cout << "List of elements before unique operation is: " ;
// starts from the first element of the list to the last
for ( auto it = list.begin(); it != list.end(); ++it)
cout << *it << " " ;
// unique operation on forward list
list.unique();
cout << "\nList of elements after unique operation is: " ;
// starts from the first element of the list to the last
for ( auto it = list.begin(); it != list.end(); ++it)
cout << *it << " " ;
return 0;
} |
Output
List of elements before unique operation is: 1 1 1 1 2 2 2 2 3 3 3 2 4 4 List of elements after unique operation is: 1 2 3 2 4
Time Complexity: O(N), where N is the number of elements compared
Auxiliary Space: O(1)