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➤微信公众号:山青咏芝(shanqingyongzhi)
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Given a collection of numbers that might contain duplicates, return all possible unique permutations.
Example:
Input: [1,1,2] Output: [ [1,1,2], [1,2,1], [2,1,1] ]
给定一个可包含重复数字的序列,返回所有不重复的全排列。
示例:
输入: [1,1,2] 输出: [ [1,1,2], [1,2,1], [2,1,1] ]
20ms
1 class Solution { 2 func permuteUnique(_ nums: [Int]) -> [[Int]] { 3 var ans = [[Int]]() 4 var nums = nums 5 permuteUnique(&nums, 0, &ans) 6 return ans 7 } 8 9 func permuteUnique(_ nums: inout [Int], _ startIndex: Int, _ ans: inout [[Int]]) { 10 if startIndex >= nums.count { 11 ans.append(nums) 12 } 13 14 var visited = Set<Int>() 15 for index in startIndex..<nums.count { 16 if visited.insert(nums[index]).inserted { 17 nums.swapAt(startIndex, index) 18 permuteUnique(&nums, startIndex+1, &ans) 19 nums.swapAt(startIndex, index) 20 } 21 } 22 } 23 }
24ms
1 class Solution { 2 func permuteUnique(_ nums: [Int]) -> [[Int]] { 3 let sortedNums = nums.sorted() 4 5 var temp = [Int]() 6 var result = [[Int]]() 7 var isvisited = Array(repeating: false, count: nums.count) 8 9 backTracking(sortedNums, &result, &temp, &isvisited) 10 return result 11 } 12 13 func backTracking(_ nums: [Int], _ result: inout [[Int]], _ temp: inout [Int], _ isvisited: inout [Bool]) { 14 if temp.count == nums.count { 15 result.append(temp) 16 return 17 } 18 19 for i in 0 ..< nums.count where !isvisited[i] { 20 if i > 0 && nums[i] == nums[i - 1] && !isvisited[i - 1]{ 21 continue 22 } 23 temp.append(nums[i]) 24 isvisited[i] = true 25 backTracking(nums, &result, &temp, &isvisited) 26 isvisited[i] = false 27 temp.removeLast() 28 } 29 30 31 } 32 }
44ms
1 class Solution { 2 private func backtrack(_ nums: [Int], _ begin: Int, results: inout [[Int]]) { 3 if begin == nums.count - 1 { 4 results.append(nums) 5 return 6 } 7 8 var nums = nums 9 10 for i in begin..<nums.count { 11 if i == begin || nums[i] != nums[begin] { 12 nums.swapAt(begin, i) 13 backtrack(nums, begin + 1, results: &results) 14 } 15 } 16 } 17 18 func permuteUnique(_ nums: [Int]) -> [[Int]] { 19 var results = [[Int]]() 20 var nums = nums.sorted() 21 backtrack(nums, 0, results: &results) 22 return results 23 } 24 }
56ms
1 class Solution { 2 func permuteUnique(_ nums: [Int]) -> [[Int]] { 3 var res = [[Int]]() 4 var index = 0 5 var nums = nums 6 helper(&res, index, &nums) 7 return res 8 } 9 10 11 private func helper(_ res: inout [[Int]], _ index: Int, _ nums: inout [Int]) { 12 if index == nums.count { 13 res.append(nums) 14 return 15 } 16 17 var usedSet = Set<Int>() 18 for i in index..<nums.count { 19 if usedSet.contains(nums[i]) { 20 continue 21 } 22 23 usedSet.insert(nums[i]) 24 nums.swapAt(index, i) 25 helper(&res, index + 1, &nums) 26 nums.swapAt(index, i) 27 } 28 } 29 }
60ms
1 class Solution { 2 var result = [[Int]]() 3 func permuteUnique(_ nums: [Int]) -> [[Int]] { 4 var nums = nums 5 permute(&nums) 6 return result 7 } 8 func permute(_ nums: inout [Int], _ index: Int = 0) { 9 if index == nums.count{ 10 result.append(nums) 11 return 12 } 13 for i in index..<nums.count{ 14 if shouldSwap(nums, index, i){ 15 nums.swapAt(index, i) 16 permute(&nums, index+1) 17 nums.swapAt(index, i) 18 } 19 } 20 } 21 22 func shouldSwap(_ nums:[Int],_ start: Int,_ current: Int) -> Bool{ 23 for i in start..<current{ 24 if nums[i] == nums[current]{ 25 return false 26 } 27 } 28 return true 29 } 30 }
76ms
1 class Solution { 2 func permuteUnique(_ nums: [Int]) -> [[Int]] { 3 4 var res = [[Int]]() 5 var path = [Int]() 6 let nums = nums.sorted() 7 var isVisited = [Bool](repeating:false,count:nums.count) 8 dfs(&res,&path,&isVisited,nums) 9 return res 10 } 11 12 func dfs(_ res:inout [[Int]],_ path:inout [Int],_ isVisited:inout [Bool],_ nums:[Int]) { 13 if path.count == nums.count { 14 res.append(path) 15 return 16 } 17 18 for (i,num) in nums.enumerated() { 19 if isVisited[i] || (i > 0 && nums[i] == nums[i-1] && !isVisited[i-1]) { 20 continue 21 } 22 23 path.append(num) 24 isVisited[i] = true 25 dfs(&res,&path,&isVisited,nums) 26 isVisited[i] = false 27 path.removeLast() 28 29 } 30 } 31 32 func toString(_ array:[Int]) -> String { 33 var str = "" 34 for (i,num) in array.enumerated() { 35 str = str + "(num)" 36 } 37 38 return str 39 } 40 }