[Swift]LeetCode216. 组合总和 III | Combination Sum III

 1 class Solution {
 2     func combinationSum3(_ k: Int,_ n: int) -> [[Int]] {
 3         guard k > 0,n > 0  else {
 4             return [[Int]]() 
 5         }
 6         
 7         var result = [[Int]]()
 8         
 9         func dfs(index:Int,target:Int,path:[Int]) {
10             if target == 0 && path.count == k {
11                 result.append(path)
12                 return
13             } else if target < 0 || index > 9 || path.count >= k {
14                 return 
15             }
16            
17             for i in index...9 {
18                 dfs(index:i + 1,target: target - i,path:path + [i])
19             }
20         }
21         dfs(index:1,target:n,path:[Int]())
22         
23         return result
24     }
25 }

 1 class Solution {
 2     func combinationSum3(_ k: Int,_ n: int) -> [[Int]] {
 3         var res = [[Int]]()
 4         var temp = [Int]()
 5         dfs(&res,&temp,n,k,1)
 6         return res
 7     }
 8     
 9     private func dfs(_ res: inout [[Int]],_ temp: inout [Int],_ n: Int,_ k: Int,_ index: int) {
10         if n == 0 && k == 0 {
11             res.append(Array(temp))
12             return
13         }
14         if n <= 0 || k == 0 || index > 9  {
15             return
16         }
17         for i in index...9 {
18             temp.append(i)
19             dfs(&res,n - i,k - 1,i + 1)
20             temp.removeLast()
21         }
22     }
23 }

 1 class Solution {
 2         func combinationSum3(_ k: Int,_ n: int) -> [[Int]] {
 3         var res = [Set<Int>]()
 4         var cur = Set<Int>()
 5         let nums : Set<Int> = [1,2,3,4,5,6,7,8,9]
 6         sumHelp(k,&cur,&res,nums)
 7         
 8         return res.map{Array($0)}
 9     }
10     
11     func sumHelp(_ k : Int,_ n : Int,_ cur : inout Set<Int>,_ res : inout [Set<Int>],_ nums : Set<Int>) {
12         if k == 1 {
13             if nums.contains(n) && !cur.contains(n) {
14                 cur.insert(n)
15                 res.append(cur)
16                 cur.remove(n)
17             }
18         }else {
19             for i in nums where i * 2 < n && i > cur.max() ?? 0 {
20                 cur.insert(i)
21                 var set = nums
22                 set.remove(i)
23                 sumHelp(k - 1,&res,set)
24                 cur.remove(i)
25             }
26         }
27     }
28 }

 1 class@H_815_502@ Solution {
 2     func combinationSum3(_ k: Int,_ n: int) ->@H_815_502@ [[Int]] { 3 var array =@H_815_502@ [Int]() 4 for i in 1 ... 9@H_815_502@ { 5 @H_815_502@ array.append(i) 6 @H_815_502@ } 7 8 var result =@H_815_502@ [[Int]]() 9 10 @H_815_502@ func Helper(remain: [Int],current: [Int],sum: int) { 11 var newRemain =@H_815_502@ remain 12 while newRemain.count > 0@H_815_502@ { 13 let temp =@H_815_502@ newRemain.removeFirst() 14 var newCurrent =@H_815_502@ current 15 @H_815_502@ newCurrent.append(temp) 16 let newSum = sum +@H_815_502@ temp 17 if newSum == n && newCurrent.count ==@H_815_502@ k { 18 @H_815_502@ result.append(newCurrent) 19 } else if newSum >@H_815_502@ n { 20 conTinue 21 } else@H_815_502@ { 22 @H_815_502@ Helper(remain: newRemain,current: newCurrent,sum: newSum) 23 @H_815_502@ } 24 @H_815_502@ } 25 @H_815_502@ } 26 27 Helper(remain: array,current: [Int](),sum: 0@H_815_502@) 28 return@H_815_502@ result 29 @H_815_502@ } 30 }

 1 import Foundation
 2 
 3 class Solution {
 4   func combinationSum3(_ k: Int,_ n: int) -> [[Int]] {
 5     var cacheMap = [String: [[Int]]]()
 6     return createConbination(count: k,target: n,prefix: [Int](),cacheMap: &cacheMap)
 7   }
 8 
 9   func createConbination(count: Int,target: Int,prefix: [Int],cacheMap: inout [String: [[Int]]]) -> [[Int]] {
10     if count == 0 || target == 0 {
11       return [prefix]
12     }
13 
14 
15     var minValue = 1
16     if let lastnumber = prefix.last {
17       minValue = lastnumber + 1
18     }
19     minValue = max(minValue,target - 9 * (count - 1))
20     let maxValue = min(9,target - (count - 1))
21     if minValue > maxValue {
22       return [[Int]]()
23     }
24 
25     let key = String(format: "%d_%d_%d",count,target,minvalue)
26     if let cachedValue = cacheMap[key] {
27       var output = [[Int]]()
28       for sequence in cachedValue {
29         var newSequence = prefix
30         let lasTindex = sequence.count - 1
31         let suffix = sequence[lasTindex - count + 1...lasTindex]
32         newSequence.append(contentsOf: suffiX)
33         output.append(newSequencE)
34       }
35       return output
36     }
37 
38     var output = [[Int]]()
39     for num in minValue...maxValue {
40       var newPrefix = prefix
41       newPrefix.append(num)
42       let newArray = createConbination(count: count - 1,target: target - num,prefix: newPrefix,cacheMap: &cacheMap)
43       output.append(contentsOf: newArray)
44     }
45 
46     cacheMap[key] = output
47     return output
48   }
49 }

 1 class Solution {
 2     func combinationSum3(_ k: Int,_ n: int) -> [[Int]] {
 3         var result: [[Int]] = []
 4         combinationSum3(k,[],1,&result)
 5         return result
 6     }
 7 
 8     func combinationSum3(_ k: Int,_ remain: Int,_ nums: [Int],_ index: Int,_ result: inout [[Int]]) {
 9         if nums.count > k || remain < 0 {
10             return
11         }
12 
13         if nums.count == k && remain == 0 {
14             result.append(nums)
15             return
16         }
17         
18         let loopCount = min(remain,9)
19         if index > loopCount {
20             return
21         }
22 
23         var nums = nums
24         for num in index...loopCount {
25             nums.append(num)
26             combinationSum3(k,remain - num,nums,num + 1,&result)
27             nums.removeLast()
28         }
29     }
30 }