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➤微信公众号：山青咏芝（shanqingyongzhi）➤博客园地址：山青咏芝（）➤GitHub地址：➤原文地址： ➤如果链接不是山青咏芝的博客园地址，则可能是爬取作者的文章。➤原文已修改更新！强烈建议点击原文地址阅读！支持作者！支持原创！★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★Given a nested list of integers, implement an iterator to flatten it.
Each element is either an integer, or a list -- whose elements may also be integers or other lists.
Example 1:
Given the list[[1,1],2,[1,1]], By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].
Example 2:
Given the list[1,[4,[6]]], By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].
给定一个嵌套的整数列表，实现一个迭代器来展平它。
每个元素要么是一个整数，要么是一个列表——其元素也可以是整数或其他列表。
例1：
给出列表[[1,1]，2，[1,1]]，
通过反复调用next，直到hasNext返回false，next返回的元素顺序应该是：[1,1,2,1,1]。
例2：
给出清单[1，[4，[6]]]，
通过重复调用next直到hasNext返回false，next返回的元素顺序应该是：[1,4,6]。
52ms
1 /** 2 * // This is the interface that allows for creating nested lists. 3 * // You should not implement it, or speculate about its implementation 4 * class NestedInteger { 5 * // Return true if this NestedInteger holds a single integer, rather than a nested list. 6 * public func isInteger() -> Bool 7 * 8 * // Return the single integer that this NestedInteger holds, if it holds a single integer 9 * // The result is undefined if this NestedInteger holds a nested list10 * public func getInteger() -> Int11 *12 * // Set this NestedInteger to hold a single integer.13 * public func setInteger(value: Int)14 *15 * // Set this NestedInteger to hold a nested list and adds a nested integer to it.16 * public func add(elem: NestedInteger)17 *18 * // Return the nested list that this NestedInteger holds, if it holds a nested list19 * // The result is undefined if this NestedInteger holds a single integer20 * public func getList() -> [NestedInteger]21 * }22 */23 24 class NestedIterator {25 26 var array = [Int]()27 var currentIterator = 028 29 init(_ nestedList: [NestedInteger]) {30 flattenList(nestedList)31 }32 33 func flattenList(_ nestedList: [NestedInteger]) {34 for element in nestedList {35 if element.isInteger() {36 array.append(element.getInteger())37 } else {38 flattenList(element.getList())39 }40 }41 }42 43 func next() -> Int {44 let val = array[currentIterator]45 currentIterator += 146 return val47 }48 49 func hasNext() -> Bool {50 return currentIterator < array.count51 }52 }53 54 /**55 * Your NestedIterator object will be instantiated and called as such:56 * let obj = NestedIterator(nestedList)57 * let ret_1: Int = obj.next()58 * let ret_2: Bool = obj.hasNext()59 */ 56ms
1 class NestedIterator { 2 private var stack = [NestedInteger]() 3 private var curr = 0 4 private var arr = [NestedInteger]() 5 init(_ nestedList: [NestedInteger]) { 6 arr = nestedList 7 } 8 9 10 private func flatternCurrentStack(){11 while !stack.isEmpty && !stack.last!.isInteger(){12 let list = stack.removeLast().getList()13 for i in stride(from: list.count - 1, through: 0 , by: -1){14 stack.append(list[i])15 }16 }17 }18 19 20 func next() -> Int {21 return stack.removeLast().getInteger()22 }23 24 func hasNext() -> Bool {25 flatternCurrentStack()26 while stack.isEmpty && curr < arr.count {27 stack.append(arr[curr])28 flatternCurrentStack()29 curr += 130 }31 return !stack.isEmpty32 }33 } 60ms
1 struct Stack2 { 3 var elements:[T] = [] 4 mutating func push(_ item:T) 5 { 6 elements.append(item) 7 } 8 mutating func pop() -> T 9 {10 return elements.removeLast() 11 }12 func isEmpty() -> Bool13 {14 return elements.isEmpty15 }16 func peek() -> T17 {18 return elements.last!19 }20 }21 class NestedIterator {22 23 var stk = Stack ()24 init(_ nestedList: [NestedInteger]) {25 for ni in stride(from:nestedList.count - 1, through:0, by: -1)26 {27 stk.push(nestedList[ni])28 }29 }30 31 func next() -> Int {32 return stk.pop().getInteger()33 }34 35 func hasNext() -> Bool {36 37 if stk.isEmpty()38 {39 return false40 }41 42 while !stk.isEmpty(){ 43 44 var top = stk.peek()45 if top.isInteger()46 {47 return true48 }49 else50 {51 stk.pop()52 53 var list = top.getList()54 55 for ni in stride(from:list.count - 1, through:0, by: -1)56 {57 stk.push(list[ni])58 }59 60 }61 }62 return false 63 }64 }
64ms
1 class NestedIterator { 2 3 var queue = [Int]() 4 5 init(_ nestedList: [NestedInteger]) { 6 makeQueue(nestedList) 7 } 8 9 func next() -> Int {10 return queue.removeFirst()11 }12 13 func hasNext() -> Bool {14 return !queue.isEmpty15 }16 17 func makeQueue(_ nestedList: [NestedInteger]) {18 for n in nestedList {19 if n.isInteger() { queue.append(n.getInteger()) }20 else { makeQueue(n.getList()) }21 }22 }23 } 68ms
1 class NestedIterator { 2 3 var stack : [NestedInteger] 4 init(_ nestedList: [NestedInteger]) { 5 stack = [] 6 append(nestedList) 7 } 8 9 func next() -> Int {10 var last = stack.first!11 stack.removeFirst()12 return last.getInteger()13 14 }15 16 func append(_ nestedList: [NestedInteger]){17 for ni in nestedList{18 if ni.isInteger(){19 stack.append(ni)20 } else{21 append(ni.getList())22 }23 }24 }25 func hasNext() -> Bool {26 guard stack.count > 0 else{27 return false28 }29 return true30 }31 } 72ms
1 class NestedIterator { 2 3 init(_ nestedList: [NestedInteger]) { 4 q = [NestedInteger]() 5 for a in nestedList { 6 q.append(a) 7 } 8 } 9 10 func next() -> Int {11 return q.removeFirst().getInteger()12 }13 14 func hasNext() -> Bool {15 while !q.isEmpty {16 let t = q.first!17 if t.isInteger() { return true }18 q.removeFirst()19 for a in t.getList().reversed() {20 q.insert(a, at: 0)21 }22 }23 return false24 }25 private var q: [NestedInteger]26 } 76ms
1 class NestedIterator { 2 3 var flattendList: [Int]! 4 5 init(_ nestedList: [NestedInteger]) { 6 flattendList = flatten(nestedList) 7 } 8 9 func flatten(_ list: [NestedInteger]) -> [Int] {10 var flatList: [Int] = []11 12 for content in list {13 if content.isInteger() { flatList.append(content.getInteger()) }14 // else { flatList += NestedIterator(content.getList()).flattendList }15 else { flatList += flatten(content.getList()) }16 }17 18 return flatList19 }20 21 func next() -> Int {22 return flattendList.removeFirst()23 }24 25 func hasNext() -> Bool {26 return !flattendList.isEmpty27 }28 } 80ms
1 class NestedIterator { 2 3 var data = [Int]() 4 5 init(_ nestedList: [NestedInteger]) { 6 self.flattenList(nestedList) 7 } 8 9 func next() -> Int {10 return self.data.removeFirst()11 }12 13 func hasNext() -> Bool {14 return self.data.count > 015 }16 17 private func flattenList(_ nestedList:[NestedInteger]){18 for n in nestedList{19 if n.isInteger(){20 self.data.append(n.getInteger())21 }else{22 self.flattenList(n.getList())23 }24 }25 }26 }