counting duplicates in c++

Question

Let\'s say I have an array of ints {100, 80, 90, 100, 80, 60}

so I want to count those duplicates and save those counter for later. because each duplicate number sh

Answer 1

Here is algo to replace elements in place if you are allowed to modify sequence:

const auto begin = std::begin( data );
const auto end = std::end( data );
std::sort( begin, end );
for( auto it = begin; it != end; ) {
    auto next = std::upper_bound( std::next( it ), end, *it );
    auto newval = *it / std::distance( it, next );
    std::fill( it, next, newval );
    it = next;
}

demo on ideone

PS modified to make it compile with array as well.