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?微信公眾號：山青詠芝（shanqingyongzhi）
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Given a?set?of candidate numbers (candidates)?(without duplicates)?and a target number (target), find all unique combinations in?candidates?where the candidate numbers sums to?target.

The?same?repeated number may be chosen from?candidates?unlimited number of times.

Note:

• All numbers (including?target) will be positive integers.
• The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [2,3,6,7], target = 7, A solution set is: [[7],[2,2,3] ]

Example 2:

Input: candidates = [2,3,5], target = 8, A solution set is: [[2,2,2,2],[2,3,3],[3,5] ]

---

給定一個無重復元素的數組?candidates?和一個目標數?target?，找出?candidates?中所有可以使數字和為?target?的組合。

candidates?中的數字可以無限制重復被選取。

說明：

• 所有數字（包括?target）都是正整數。
• 解集不能包含重復的組合。?

示例?1:

輸入: candidates = [2,3,6,7], target = 7, 所求解集為: [[7],[2,2,3] ]

示例?2:

輸入: candidates = [2,3,5], target = 8, 所求解集為: [[2,2,2,2],[2,3,3],[3,5] ]

---

20ms 1 class Solution { 2 var result = [[Int]]() 3 func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] { 4 combinationSum(candidates, target, 0, [Int]()) 5 return result 6 } 7 8 func combinationSum(_ candidates: [Int], _ target: Int, _ currentInex: Int, _ usdedNums: [Int]) { 9 if target <= 0 { 10 if target == 0 { 11 result.append(usdedNums) 12 } 13 return 14 } 15 for i in currentInex..<candidates.count { 16 let currentValue = candidates[i] 17 if currentValue > target { 18 continue 19 } 20 var usdedNumsCopy = usdedNums 21 usdedNumsCopy.append(currentValue) 22 combinationSum(candidates, target-currentValue, i, usdedNumsCopy) 23 } 24 } 25 }

---

24ms

1 class Solution { 2 func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] { 3 let candidatesCopy = candidates.sorted{ $0 < $1 } 4 var tmp = [Int]() 5 var res = [[Int]]() 6 var index = 0 7 helper(&tmp, &res, index, candidatesCopy, target) 8 return res 9 } 10 11 private func helper(_ tmp: inout [Int], _ res: inout [[Int]], _ index: Int, _ candidatesCopy: [Int], _ target: Int) { 12 if target == 0 { 13 res.append(tmp) 14 return 15 }else if index == candidatesCopy.count { 16 return 17 } 18 19 for i in index..<candidatesCopy.count { 20 if candidatesCopy[i] > target { 21 return 22 }else if i != index && candidatesCopy[i] == candidatesCopy[i - 1] { 23 continue 24 } 25 26 tmp.append(candidatesCopy[i]) 27 helper(&tmp, &res, i, candidatesCopy, target - candidatesCopy[i]) 28 tmp.removeLast() 29 } 30 } 31 }

---

28ms

1 class Solution { 2 func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] { 3 var result = [[Int]]() 4 var out = [Int]() 5 var candidates = candidates.sorted() 6 combinationSumDFS(candidates, target, 0, &out, &result) 7 return result 8 } 9 10 func combinationSumDFS(_ candidates: [Int], _ target: Int, _ start: Int, _ out: inout [Int], _ res: inout [[Int]]) { 11 if target == 0 { 12 res.append(out) 13 } else { 14 for i in start..<candidates.count { 15 guard target - candidates[i] >= 0 else { 16 break 17 } 18 out.append(candidates[i]) 19 combinationSumDFS(candidates, target - candidates[i], i, &out, &res) 20 out.remove(at: out.count - 1) 21 22 } 23 } 24 } 25 26 }

---

28ms

1 class Solution { 2 3 var list = [[Int]]() 4 5 func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] { 6 var currentlySelected = [Int]() 7 recursiveCombSum(candidates: candidates, index: 0, target: target, currentlySelected: currentlySelected) 8 return list 9 } 10 11 func recursiveCombSum(candidates: [Int], index: Int, target: Int, currentlySelected: [Int]) { 12 if 0 == target { 13 list += [currentlySelected] 14 } 15 if index == candidates.count { 16 } else { 17 for i in index..<candidates.count { 18 if candidates[i] <= target { 19 var newTarget = target - candidates[i] 20 var newList = currentlySelected + [candidates[i]] 21 recursiveCombSum(candidates: candidates, index: i, target: newTarget, currentlySelected: newList) 22 } 23 } 24 } 25 } 26 }

---

56ms

1 class Solution { 2 var conbineArray = [[Int]]() 3 func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] { 4 let count = candidates.count 5 guard count > 0 else { 6 return [[Int]]() 7 } 8 combine(candidates, [Int](), count, 0, target) 9 return conbineArray 10 } 11 12 func combine(_ candidates: [Int], _ currentCombine: [Int], _ count: Int, _ index: Int, _ target: Int) { 13 if target < 0 { return } 14 if index == count { return } 15 if target == 0 { 16 conbineArray.append(currentCombine) 17 return 18 } 19 20 combine(candidates, currentCombine, count, index + 1, target) 21 var currentCombine = currentCombine 22 currentCombine.append(candidates[index]) 23 combine(candidates, currentCombine, count, index, target - candidates[index]) 24 } 25 }

?

轉載于:https://www.cnblogs.com/strengthen/p/9900712.html

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