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  1. Lonely Integer
  2. Discussions

Lonely Integer

  • cbiggin
     + 0 comments

    Swift:

    func lonelyinteger(a: [Int]) -> Int {
    var dict = [Int: Bool]()
    
    a.forEach { value in
        // will nil the dictionary entry if more than 1 occurrence
        if dict[value] != nil {
            dict[value] = nil
        } else {
            dict[value] = true
        }
    }
    
    // should only be 1 entry left
    return dict.keys.first ?? -1
}