Credit: This example is from the book Effective Java Item 16: Favour composition over inheritance by Joshua Bloch. We want to build a HashSet, which can count the number of elements added since the ...
// where 'n' is the length of 'arr', as we traverse 'arr' when recording the frequency in the counting array, // and half of 'k' when traversing the counting array to check for the pairs summing up to ...