Sure. The distinct() method in C++ can be used to remove duplicate elements from a sequence. The distinct() method takes an optional parameter that specifies the comparer to use when comparing elements. If the parameter is 0, the default comparer is used. The default comparer compares elements by their GetHashCode() method.

Lambda expressions can be used to provide a custom comparer to the distinct() method. The following code is an example of how to use a lambda expression with the distinct() method:

C++

#include <iostream>
#include <vector>

using namespace std;

int main() {
  vector<int> numbers = {1, 2, 3, 2, 1};

  // Use a lambda expression to define a custom comparer.
  auto comparer = [](int x, int y) { return x < y; };

  // Remove the duplicates from the vector.
  numbers = numbers.distinct(comparer);

  // Print the elements of the vector.
  for (int number : numbers) {
    cout << number << " ";
  }

  cout << endl;

  return 0;
}

In this code, the comparer lambda expression defines a custom comparer that compares two integers and returns a value indicating whether the first integer is less than the second integer. The distinct() method uses the comparer lambda expression to remove the duplicates from the numbers vector.