PickingNumbers HackerRank - Solving

.swift

func pickingNumbers(a: [Int]) -> Int {
    var repeatList = Array(repeating: 0, count: 100) //Generated list with 100 zeros
    for i in 0..<a.count {           //Count repeating of each item in input array
        repeatList[a[i] - 1] += 1
    }
    var result = 0
    for i in 0..<(repeatList.count - 1) {
        let stepSum = repeatList[i] + repeatList[i + 1] //Sum of each item and next item
        if stepSum > result { //The biggest met sum is our answer
            result = stepSum
        }
    }
    return result
}