std::erase_if (std::flat_multiset)

#include <iostream>
#include <flat_set>
 
void println(auto rem, const auto& container)
{
 std::cout << rem << '{';
 for (char sep[]{0, ' ', 0}; const auto& item : container)
 std::cout << sep << item, *sep = ',';
 std::cout << "}\n";
}
 
int main()
{
 std::flat_multiset data{3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0};
 println("Original:\n", data);
 
 auto divisible_by_3 = [](const auto& x) { return (x % 3) == 0; };
 
 const auto count = std::erase_if (data, divisible_by_3);
 
 println("Erase all items divisible by 3:\n", data);
 std::cout << count << " items erased.\n";
}

Original:
{0, 1, 2, 3, 3, 4, 5, 5, 6, 6, 7}
Erase all items divisible by 3:
{1, 2, 4, 5, 5, 7}
5 items erased.