[Swift]LeetCode163. 缺失区间 $ Missing Ranges

Given a sorted integer array where the range of elements are [0, 99] inclusive, return its missing ranges.
For example, given [0, 1, 3, 50, 75], return [“2”, “4->49”, “51->74”, “76->99”]

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给定一个排序的整数数数组，其中元素的范围包含[0,99]，返回其缺少的范围。

例如，给定[0，1，3，50，75]，返回[“2”，“4->49”，“51->74”，“76->99”]

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 1 class Solution {
 2     func findMissingRanges(_ nums:[Int] ,_ lower:Int,_ upper:Int) -> [String]{
 3         var res:[String] = [String]()
 4         var l:Int = lower
 5         for i in 0...nums.count
 6         {
 7             var r:Int = (i < nums.count && nums[i] <= upper) ? nums[i] : upper + 1
 8             if l == r
 9             {
10                 l += 1
11             }
12             else if r > l
13             {
14                 res.append(r - l == 1 ? String(l):String(l) + "->" + String(r - 1))
15                 l = r + 1
16             }
17         }
18         return res
19     }
20 }