simonracz

// Explanation
//    0 1 2 3 4
// 0 |  o o o o|
// 1 |o   o o o|
// 2 |o o   o o|
// 3 |o o o   o|
// 4 |o o o o  |
//
// Goal is to "sum up" the dots in each columns. (Dot represents a product of course not a sum)
// I do that by first "summing up" the upper triangle, then the lower triangle

simonracz

import Foundation

extension Set {

    mutating func nonUpdatingInsert(member: Element) {
        if !self.contains(member) {
            self.insert(member)
        }
    }