1 class Solution {
 2     func numRabbits(_ answers: [Int]) -> Int {
 3         var res:Int = 0
 4         var m:[Int:Int] = [Int:Int]()
 5         for ans in answers
 6         {
 7             m[ans,default:0] += 1
 8         }
 9         for (key,val) in m
10         {
11             res += (val + key) / (key + 1) * (key + 1)
12         }
13         return res
14     }
15 }

 1 class Solution {
 2     func numRabbits(_ answers: [Int]) -> Int {
 3         var counter = [Int: Int]()
 4         answers.forEach{ counter[$0, default: 0] += 1 }
 5
 6         var ret = 0
 7         for (n, c) in counter {
 8             let colors = (c + n) / (n + 1)
 9             ret += colors * (n + 1)
10         }
11         return ret
12     }
13 }

 1 class Solution {
 2     func numRabbits(_ answers: [Int]) -> Int {
 3         if answers.count == 0 {
 4         return 0
 5     }
 6
 7     let sortAns = answers.sorted()
 8     var first = -1
 9
10     var total = 0
11     var sep = 0
12
13     for (_, itemCount) in sortAns.enumerated() {
14         if itemCount != first || sep == first {
15             first = itemCount
16             sep = 0
17
18             total += 1 + itemCount
19         } else {
20             sep += 1
21         }
22     }
23     return total
24     }
25 }

 1 class Solution {
 2     func numRabbits(_ answers: [Int]) -> Int {
 3         var mark = [Int : Int]()
 4         for answer in answers {
 5             if let count = mark[answer] {
 6                 mark[answer] = count + 1
 7             } else {
 8                 mark[answer] = 1
 9             }
10         }
11
12         var result = 0
13         for (key, value) in mark {
14             let groupNum = key + 1
15             var group = value / groupNum
16             if value % groupNum != 0 {
17                 group += 1
18             }
19             result += group * groupNum
20         }
21         return result
22     }
23 }