majority-element/majority-element.swift at master · dkhofer/majority-element · GitHub

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func majorityElement(input: [Int]) -> Int? {
    var counts = [Int:Int]()
    for element in input {
    	if let value = counts[element] {
	    counts[element] = value + 1
    	} else {
       	    counts[element] = 1
    	}
    }

    var result: Int?
    for (element, count) in counts {
    	if count > input.count / 2 {
            result = element
    	}
    }

    return result
}

// NOTE(hofer, 2014-10-26): Currently I'm not aware of a way to read arbitrary files (ie not inside of an ios app) in Swift, so this is a copy-and-paste of contents of small-input.txt.
var input = [1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,2,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]

println(majorityElement(input));