Given a non-empty array of non-negative integers nums, the degreeof this array is defined as the maximum frequency of any one of its elements.
Your task is to find the smallest possible length of a (contiguous) subarray of nums, that has the same degree as nums.
Example 1:
Input: [1, 2, 2, 3, 1] Output: 2 Explanation: The input array has a degree of 2 because both elements 1 and 2 appear twice. Of the subarrays that have the same degree: [1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2] The shortest length is 2. So return 2.
Example 2:
Input: [1,2,2,3,1,4,2] Output: 6
Note:
nums.lengthwill be between 1 and 50,000.nums[i]will be an integer between 0 and 49,999.
给定一个非空且只包含非负数的整数数组 nums, 数组的度的定义是指数组里任一元素出现频数的最大值。
你的任务是找到与 nums 拥有相同大小的度的最短连续子数组，返回其长度。
示例 1:
输入: [1, 2, 2, 3, 1] 输出: 2 解释: 输入数组的度是2，因为元素1和2的出现频数最大，均为2. 连续子数组里面拥有相同度的有如下所示: [1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2] 最短连续子数组[2, 2]的长度为2，所以返回2.
示例 2:
输入: [1,2,2,3,1,4,2] 输出: 6
注意:
nums.length在1到50,000区间范围内。nums[i]是一个在0到49,999范围内的整数。
Runtime: 220 ms
Memory Usage: 20.5 MB
1 class Solution { 2 func findShortestSubArray(_ nums: [Int]) -> Int { 3 guard nums.count > 1 else { 4 return nums.count 5 } 6 var dic: [Int:Int] = [:] 7 for i in 0..<nums.count { 8 let num: Int = nums[i] 9 if dic.keys.contains(num) { 10 dic[num] = dic[num]! + 1 11 } else { 12 dic[num] = 1 13 } 14 } 15 var max = 0//出现最大次数 16 var maxNums: [Int] = []//出现最大次数元素数组 17 for j in dic.keys { 18 let v = dic[j]! 19 if v > max { 20 maxNums.removeAll() 21 maxNums.append(j) 22 max = v 23 } else if v == max { 24 maxNums.append(j) 25 } 26 } 27 if max < 2 { 28 return 1 29 } 30 var minChildArrayCount = nums.count//最短连续子数组长度 31 for a in maxNums { 32 var start: Int = 0,end: Int = nums.count-1//开始位置，结束位置 33 for s in nums { 34 if s != a { 35 start += 1 36 } else { 37 break 38 } 39 } 40 for e in nums.reversed() { 41 if e != a { 42 end -= 1 43 } else { 44 break 45 } 46 } 47 minChildArrayCount = min(minChildArrayCount, end-start+1) 48 } 49 return minChildArrayCount 50 } 51 }
228ms
1 class Solution { 2 func findShortestSubArray(_ nums: [Int]) -> Int { 3 var starts = [Int: Int]() 4 var ends = [Int: Int]() 5 var counts = [Int: Int]() 6 var maxCount = Int.min 7 8 for i in 0..<nums.count { 9 let num = nums[i] 10 if starts[num] == nil { 11 starts[num] = i 12 } 13 ends[num] = i 14 counts[num] = ( counts[num] ?? 0 ) + 1 15 maxCount = max(counts[num]!, maxCount) 16 } 17 18 var result = Int.max 19 for key in counts.keys { 20 if counts[key]! < maxCount { 21 continue 22 } 23 24 result = min(ends[key]! - starts[key]! + 1, result) 25 } 26 27 return result 28 } 29 }
240ms
1 class Solution { 2 func findShortestSubArray(_ nums: [Int]) -> Int { 3 var dict = [Int: [Int]]() 4 var frequency = Dictionary( nums.map{ ($0, 1) }, uniquingKeysWith: +) 5 var degree = 0 6 for (key, value) in frequency { 7 degree = max(value, degree) 8 } 9 var degreeItemArray = Set<Int>() 10 for (key, value) in frequency { 11 if value == degree { 12 degreeItemArray.insert(key) 13 } 14 } 15 for i in 0..<nums.count { 16 guard degreeItemArray.contains(nums[i]) else { 17 continue 18 } 19 dict[nums[i]] = dict[nums[i]] ?? [i, i] 20 var items = dict[nums[i]]! 21 if i > items[1] { 22 items[1] = i 23 } 24 dict[nums[i]] = items 25 } 26 var result = Int.max 27 for (key, value) in dict { 28 result = min(result, value[1] - value[0] + 1) 29 } 30 return result 31 } 32 }
264ms
1 class ItemInfo { 2 let value: Int 3 var count: Int 4 var startIndex: Int 5 var endIndex: Int 6 7 var length: Int { 8 return self.endIndex - self.startIndex + 1 9 } 10 11 init(value: Int, at index: Int) { 12 self.value = value 13 self.count = 1 14 self.startIndex = index 15 self.endIndex = index 16 } 17 18 func addItem(at index: Int) -> Self { 19 self.count += 1 20 self.startIndex = min(startIndex, index) 21 self.endIndex = max(endIndex, index) 22 23 return self 24 } 25 } 26 27 class Solution { 28 func findShortestSubArray(_ nums: [Int]) -> Int { 29 guard nums.count > 1 else { 30 return nums.count 31 } 32 33 var info: [Int: ItemInfo] = [:] 34 35 for (index, num) in nums.enumerated() { 36 if let currentInfo = info[num] { 37 info[num] = currentInfo.addItem(at: index) 38 } else { 39 info[num] = ItemInfo(value: num, at: index) 40 } 41 } 42 43 if let max = info.max(by: { (arg1, arg2) -> Bool in 44 return arg1.value.count < arg2.value.count || (arg1.value.count == arg2.value.count && arg1.value.length > arg2.value.length) 45 }) { 46 return max.value.length 47 } else { 48 return -1 49 } 50 } 51 }
284ms
1 class Solution { 2 func findShortestSubArray(_ nums: [Int]) -> Int { 3 var firstIndexMap = [Int: Int]() 4 var lastIndexMap = [Int: Int]() 5 var countMap = [Int: Int]() 6 7 // Find the "degree" (most frequent element count) 8 var maxCount = 0 9 for (i, num) in nums.enumerated() { 10 if let count = countMap[num] { 11 maxCount = max(maxCount, count + 1) 12 countMap[num] = count + 1 13 lastIndexMap[num] = i 14 } else { 15 countMap[num] = 1 16 firstIndexMap[num] = i 17 } 18 19 maxCount = max(maxCount, countMap[num]!) 20 } 21 22 guard maxCount > 1 else { return maxCount } 23 24 let maxDict = countMap.filter { k, v in v == maxCount } 25 26 var lengthsDict = [Int: Int]() 27 for (key, _) in maxDict { 28 lengthsDict[key] = lastIndexMap[key]! - firstIndexMap[key]! + 1 29 } 30 31 let minValue = [Int](lengthsDict.values).min() ?? 0 32 33 return minValue 34 } 35 }
440ms
1 class Solution { 2 func findShortestSubArray(_ nums: [Int]) -> Int { 3 4 if nums.count <= 1 { 5 return nums.count 6 } 7 8 var dict = [Int: [String: Int]]() 9 10 for i in 0..<nums.count { 11 12 let value = nums[i] 13 14 if dict[value] == nil { 15 dict[value] = [ 16 "start": i, 17 "end": i, 18 "count": 1 19 ] 20 } else { 21 dict[value]!["end"] = i 22 dict[value]!["count"] = dict[value]!["count"]! + 1 23 } 24 } 25 26 var count = Int.min 27 var degree = Int.max 28 29 for key in dict.keys { 30 31 let d = dict[key] 32 33 guard let c = d!["count"] else { 34 continue 35 } 36 37 if c < count { 38 continue 39 } 40 41 guard let s = d!["start"] else { 42 continue 43 } 44 45 guard let e = d!["end"] else { 46 continue 47 } 48 49 if c > count { 50 degree = e - s + 1 51 } else { 52 degree = min(degree, e - s + 1) 53 } 54 55 count = max(count, c) 56 } 57 58 return degree == Int.max ? 1 : degree 59 } 60 }