[Swift]LeetCode752. 打开转盘锁 | Open the Lock

概述You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘. The wheels can rotate freely and wrap around: for example we can turn

You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: ‘0‘,‘1‘,‘2‘,‘3‘,‘4‘,‘5‘,‘6‘,‘7‘,‘8‘,‘9‘. The wheels can rotate freely and wrap around: for example we can turn ‘9‘ to be ‘0‘,or ‘0‘ to be ‘9‘. Each move consists of turning one wheel one slot.

The lock initially starts at ‘0000‘,a string representing the state of the 4 wheels.

You are given a List of deadends dead ends,meaning if the lock displays any of these codes,the wheels of the lock will stop turning and you will be unable to open it.

Given a target representing the value of the wheels that will unlock the lock,return the minimum total number of turns required to open the lock,or -1 if it is impossible.

Example 1:

input: deadends = ["0201","0101","0102","1212","2002"],target = "0202"Output: 6Explanation:A sequence of valID moves would be "0000" -> "1000" -> "1100" -> "1200" -> "1201" -> "1202" -> "0202".Note that a sequence like "0000" -> "0001" -> "0002" -> "0102" -> "0202" would be invalID,because the wheels of the lock become stuck after the display becomes the dead end "0102".

Example 2:

input: deadends = ["8888"],target = "0009"Output: 1Explanation:We can turn the last wheel in reverse to move from "0000" -> "0009". 

Example 3:

input: deadends = ["8887","8889","8878","8898","8788","8988","7888","9888"],target = "8888"Output: -1Explanation:We can‘t reach the target without getting stuck. 

Example 4:

input: deadends = ["0000"],target = "8888"Output: -1 

Note:

The length of deadends will be in the range [1,500]. target will not be in the List deadends. Every string in deadends and the string target will be a string of 4 digits from the 10,000 possibilitIEs ‘0000‘ to ‘9999‘.

你有一个带有四个圆形拨轮的转盘锁。每个拨轮都有10个数字： ‘0‘,‘9‘ 。每个拨轮可以自由旋转：例如把 ‘9‘ 变为  ‘0‘，‘0‘ 变为 ‘9‘ 。每次旋转都只能旋转一个拨轮的一位数字。

锁的初始数字为 ‘0000‘ ，一个代表四个拨轮的数字的字符串。

列表 deadends 包含了一组死亡数字，一旦拨轮的数字和列表里的任何一个元素相同，这个锁将会被永久锁定，无法再被旋转。

字符串 target 代表可以解锁的数字，你需要给出最小的旋转次数，如果无论如何不能解锁，返回 -1。 

示例 1:

输入：deadends = ["0201",target = "0202"输出：6解释：可能的移动序列为 "0000" -> "1000" -> "1100" -> "1200" -> "1201" -> "1202" -> "0202"。注意 "0000" -> "0001" -> "0002" -> "0102" -> "0202" 这样的序列是不能解锁的，因为当拨动到 "0102" 时这个锁就会被锁定。

示例 2:

输入: deadends = ["8888"],target = "0009"输出：1解释：把最后一位反向旋转一次即可 "0000" -> "0009"。

示例 3:

输入: deadends = ["8887",target = "8888"输出：-1解释：无法旋转到目标数字且不被锁定。

示例 4:

输入: deadends = ["0000"],target = "8888"输出：-1 

提示：

死亡列表 deadends 的长度范围为 [1,500]。 目标数字 target 不会在 deadends之中。 每个 deadends 和 target 中的字符串的数字会在 10,000 个可能的情况 ‘0000‘ 到 ‘9999‘ 中产生。 Runtime: 296 ms Memory Usage: 20.1 MB

 1 class Solution { 2     func openLock(_ deadends: [String],_ target: String) -> Int { 3         var start: Set<String> = [] 4         var end: Set<String> = [] 5         let deadends: Set<String> = Set(deadends) 6          7         var startToNow: Set<String> = [] 8         var endToNow: Set<String> = [] 9 10         start.insert("0000")11         end.insert(target)12         13         startToNow.insert("0000")14         endToNow.insert(target)15         16         var steps = 017         18         // Tip: Start from both sIDes19         while !start.isEmpty && !end.isEmpty {20             var temp: Set<String> = []21                         22             if !start.intersection(end).isEmpty {23                 return steps24             }25             26             for s in start {27                 if deadends.contains(s) { continue }28                 29                 for next in getNext(s) {30                     if !deadends.contains(next) && !startToNow.contains(next) {31                         temp.insert(next)32                     }33                 }34             }35             steps += 136             37             (start,end) = (end,temp)38             (startToNow,endToNow) = (endToNow,startToNow.union(temp))39         }40         41         return -142     }43     44     private func getNext(_ s: String) -> Set<String> {45         var s: [Int] = Array(s).map{ return Int(String($0))! }46         var res: Set<String> = []47         48         for i in  0 ..< 4 {49             var t = s50             t[i] = (s[i] + 1) % 1051             res.insert(t.reduce("",{ return $0 + String($1) }))52             t[i] = (s[i] - 1 + 10) % 1053             res.insert(t.reduce("",{ return $0 + String($1) }))54         }55         return res56     }57 }

560ms

  1 class Solution {  2     struct Value: Hashable,customstringconvertible {  3         let v1: Int  4         let v2: Int  5         let v3: Int  6         let v4: Int  7   8         init(v1: Int,v2: Int,v3: Int,v4: Int) {  9             self.v1 = v1 10             self.v2 = v2 11             self.v3 = v3 12             self.v4 = v4 13         } 14  15         init(value: Int) { 16             let digits = Value.convertToDigits(number: value) 17  18             self.init(v1: digits[0],v2: digits[1],v3: digits[2],v4: digits[3]) 19         } 20  21         var nextValues: [Value] { 22             return [ 23                 Value(v1: v1.incrementDecimal(),v2: v2,v3: v3,v4: v4), 24                 Value(v1: v1.decrementDecimal(), 25                 Value(v1: v1,v2: v2.incrementDecimal(), 26                 Value(v1: v1,v2: v2.decrementDecimal(), 27                 Value(v1: v1,v3: v3.incrementDecimal(), 28                 Value(v1: v1,v3: v3.decrementDecimal(), 29                 Value(v1: v1,v4: v4.incrementDecimal()), 30                 Value(v1: v1,v4: v4.decrementDecimal()), 31             ] 32         } 33  34         var description: String { 35             return "\(v1)\(v2)\(v3)\(v4)" 36         } 37  38         private static func convertToDigits(number: Int) -> [Int] { 39             let first = number % 10 40             let second = (number % 100) / 10 41             let third = (number % 1000) / 100 42             let fourth = (number % 10000) / 1000 43  44             return [fourth,third,second,first] 45         } 46     } 47  48     class Combination: Hashable { 49         let value: Value 50         let step: Int 51  52         init(value: Value,step: Int) { 53             self.value = value 54             self.step = step 55         } 56  57         var hashValue: Int { 58             return value.hashValue 59         } 60  61         static func == (lhs: Solution.Combination,rhs: Solution.Combination) -> Bool { 62             return lhs.value == rhs.value 63         } 64     } 65  66     private var queue: [Combination] = [] 67     private var queuedValues: Set<Value> = [] 68  69     func openLock(_ deadends: [String],_ target: String) -> Int { 70         let convertedDeadends = deadends.map { Int($0)! } 71         let convertedTarget = Int(target)! 72  73         return openLock(convertedDeadends,convertedTarget) 74     } 75  76     private func openLock(_ deadends: [Int],_ target: Int) -> Int { 77         let initialCombination = Combination(value: Value(value: 0),step: 0) 78         let targetValue = Value(value: target) 79         let deadendValues = Set(deadends.map { Value(value: $0) }) 80  81         queue.append(initialCombination) 82  83         while !queue.isEmpty { 84             let combination = queue.removeFirst() 85  86             guard !deadendValues.contains(combination.value) else { continue } 87             if combination.value == targetValue { 88                 return combination.step 89             } 90  91             enqueuePossibleCombinations(from: combination) 92         } 93  94         return -1 95     } 96  97     private func enqueuePossibleCombinations(from combination: Combination) { 98         let nextStep = combination.step + 1 99 100         combination.value.nextValues.forEach {101             enqueueIfPossible(value: $0,step: nextStep)102         }103     }104 105     private func enqueueIfPossible(value: Value,step: Int) {106         guard !queuedValues.contains(value) else { return }107         queuedValues.insert(value)108 109         let combination = Combination(value: value,step: step)110         queue.append(combination)111     }112 }113 114 extension Int {115     func incrementDecimal() -> Int {116         return (self + 1) % 10117     }118 119     func decrementDecimal() -> Int {120         return (self - 1 + 10) % 10121     }122 }

696ms

 1 final class Solution { 2      3     func openLock(_ deadends: [String],_ target: String) -> Int { 4         let deadends = Set(deadends.map { str in 5             Array(str).map { Int(String($0))! } 6         }) 7         let target = Array(target).map { Int(String($0))! } 8         let start = [0,0,0] 9         var q = Queue<[Int]>()10         var visited = Set<[Int]>()11         q.push(start)12         visited.insert(start)13         var count = 014         while !q.isEmpty {15             let size = q.size16             for i in 0..<q.size {17                 let node = q.pop()18                 if deadends.contains(node) { continue }19                 if target == node { return count }20                 for (i,digit) in node.enumerated() {21                     var neighbor = node22                     neighbor[i] = (digit + 1) % 1023                     if !visited.contains(neighbor) {24                         q.push(neighbor)25                         visited.insert(neighbor)26                     }27                     neighbor = node28                     neighbor[i] = (digit - 1)29                     if neighbor[i] == -1 { neighbor[i] = 9 }30                     if !visited.contains(neighbor) {31                         q.push(neighbor)32                         visited.insert(neighbor)33                     }34                 }35             }36             count += 137         }38         return -139     }40 }41 42 struct Queue<T> {43     var arr = [T]()44     var head = 045     46     mutating func push(_ val: T) {47         arr.append(val)48     }49     50     mutating func pop() -> T {51         let res = arr[head]52         head += 153         return res54     }55     56     var isEmpty: Bool {57         return head >= arr.count58     }59     60     var size: Int {61         return arr.count - head62     }63 }

704ms

 1 typealias Combo = [Int] 2  3 class Solution { 4     func openLock(_ deadends: [String],_ target: String) -> Int { 5         let target = Array(target).compactMap {Int(String($0)) } 6         let start = [0,0] 7         var seen = Set<Combo>() 8  9         for word in deadends {10             seen.insert(Array(word).map { Int(String($0))! })11         }12         guard !seen.contains(start) else { return -1 }13         var q: [Combo] = [start]14         var level = 015 16         while !q.isEmpty {17             18             var tempQ: [Combo] = []19             for current in q {20                 guard current != target else { return level }21                 seen.insert(current) // add to deadends/visited List22 23                 for i in 0 ..< current.count {24                     var nextValue = current25                     nextValue[i].next()26 27                 if !seen.contains(nextValue) {28                     tempQ.append(nextValue)29                     seen.insert(nextValue)30                 }31 32                 var prevValue = current33                 prevValue[i].prev()34 35                 if !seen.contains(prevValue) {36                     tempQ.append(prevValue)37                     seen.insert(prevValue)38                 }39                 }40             }41             level += 142             q = tempQ43 44         }45         return -146     }47 }48 49 extension Int {50     mutating func next() {51         self = (self + 1) % 1052     }53     mutating func prev() {54         self = (self + 10 - 1) % 1055     }56 }

772ms

 1 class Solution { 2     func openLock(_ deadends: [String],_ target: String) -> Int { 3         let target = Array(target).map{ Int("\(") })! 40         let deadends = Set(Array(deadends).map{ $".map{ Int(\(") } }) 5)!var()          6 visited = Set<[Int]>var0         0 queue = [([0,)]], 7var0          8 i = while queue.count {          9 i != queue[i]10             let (candIDate,index) =111             i += ifcontinue              } visited.contains(candIDate) || deadends.contains(candIDate) { 12ifreturn              index } candIDate == target { 13            visited.insert(candIDate)14 forin             0 j 3  {...15var candIDate                 16 c =19                 c[j] = (c[j] + 17) % 1))                  queue.append((c,index+18            }19 forin             0 j 3  {...20var candIDate                 21 c =09                 c[j] = c[j] == 1 ? 22 : c[j] - 1))                 queue.append((c,index+23            }24 if100000             return i > 10000 { } -25        }26 return1         27 -    }28  1class }

784ms

 Solution {  2 queue[i]10     func openLock(_ deadends: [String],index) =111             i += ifcontinue              } visited.contains(candIDate) || deadends.contains(candIDate) { 12ifreturn              index } candIDate == target { 13            visited.insert(candIDate)14 forin             0 j 3  {...15var candIDate                 16 c =var c[j]                 17 cj =19                 c[j] = (cj + 18) % 1))                 queue.append((c,index+1909                 c[j] = cj == 1 ? 20 : cj - 1))                 queue.append((c,index+21            }22         }23 return1         24 -    }25  1class }

Runtime: 864 ms Memory Usage: 20.3 MB

 Solution {  2 Int { 3     func openLock(_ deadends: [String],_ target: String) ->var(deadends)          4 deadlock:Set<String> = Set<String>if"         0000 deadlock.contains(") 5        { 6 return1              7 -        } 8 var0          9 res:Int = var"         0000 visited:Set<String> = ["]10var"         0000 q:[String] = ["]11whileq.isEmpty)         12(!        {13 114             res += forin             from k 0 strIDe(1:q.count,to:),by:-15            {16  q.removeFirst()17                 let t:String = Array(t)18                 let arrChar:[Character] =0.ascii}                 let arrInt:[Int] = arrChar.map{$19forin                 0 i t.count 20..<                {21 var arrChar[i]                     22 c:Character =var arrInt[i]                     23 num:Int =var0                     " str1:String = t.subString(9,i) + String(c == "048 ? 1 : num - 1 + )) + t.subString(i + 24var0                     " str2:String = t.subString(0,i) + String(c == "948 ? 1 : num - 1 - )) + t.subString(i + 25if target                     26 str1 == target || str2 ==                    {27 return res                         28                    }29 ifdeadlock.contains(str1)                     30 !visited.contains(str1) && !                    {31                         q.append(str1)32                     }33 ifdeadlock.contains(str2)                     34 !visited.contains(str2) && !                    {35                         q.append(str2)36                     }37                     visited.insert(str1)38                     visited.insert(str2)                    39                 }                40             }41         }42 return1         43 -    }44 }45 46// Character扩展  47extension Character  48 {  49 //Character转ASCII整数值(定义小写为整数值)   50var ascii: Int {    51get {        52return0            ) Int(self.unicodeScalars.first?.value ?? 53       }       54     }    55 }56 57extension String { 58 // 截取字符串：指定索引和字符数     59// - begin: 开始截取处索引     60// - count: 截取的字符数量     61 String {62     func subString(_ begin:Int,_ count:Int) ->0,begin))         let start = self.index(self.startIndex,offsetBy: max(63 count))64         let end = self.index(self.startIndex,offsetBy:  min(self.count,begin +returnend])          65 String(self[start..<    }66 67//      截取字符串：从index到结束处     68// - Parameter index: 开始索引     69// - Returns: 子字符串     70 String {71     func subString(_ index: Int) -> self.count)72         let theIndex = self.index(self.endindex,offsetBy: index -returnendindex])         73 String(self[theIndex..<    }74  }

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