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➤微信公众号：山青咏芝（shanqingyongzhi）
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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
(i.e., [0,0,1,2,2,5,6] might become [2,5,6,0,0,1,2]).
You are given a target value to search. If found in the array return true, otherwise return false.
Example 1:
Input: nums = [2,5,6,0,0,1,2], target = 0
Output: true
Example 2:
Input: nums = [2,5,6,0,0,1,2], target = 3
Output: false
Follow up:
- This is a follow up problem to Search in Rotated Sorted Array, where
numsmay contain duplicates. - Would this affect the run-time complexity? How and why?
假设按照升序排序的数组在预先未知的某个点上进行了旋转。
( 例如，数组 [0,0,1,2,2,5,6] 可能变为 [2,5,6,0,0,1,2] )。
编写一个函数来判断给定的目标值是否存在于数组中。若存在返回 true，否则返回 false。
示例 1:
输入: nums = [2,5,6,0,0,1,2], target = 0
输出: true
示例 2:
输入: nums = [2,5,6,0,0,1,2], target = 3
输出: false
进阶:
- 这是 搜索旋转排序数组 的延伸题目，本题中的
nums可能包含重复元素。 - 这会影响到程序的时间复杂度吗？会有怎样的影响，为什么？
12ms
1 class Solution { 2 func search(_ nums: [Int], _ target: Int) -> Bool { 3 if nums.count == 0 { 4 return false 5 } 6 7 var left = 0 8 var right = nums.count - 1 9 10 while left < right { 11 let middle = left + (right - left) / 2 12 if nums[middle] == target { 13 return true 14 } 15 if nums[middle] > nums[right] { 16 if nums[middle] > target && nums[left] <= target { 17 right = middle 18 } else { 19 left = middle + 1 20 } 21 } else if nums[middle] < nums[right] { 22 if nums[middle] < target && nums[right] >= target { 23 left = middle + 1 24 } else { 25 right = middle 26 } 27 } else { 28 right -= 1 29 } 30 } 31 32 return nums[left] == target 33 } 34 }
16ms
1 class Solution { 2 func search(_ nums: [Int], _ target: Int) -> Bool { 3 4 if nums.count <= 0 { return false } 5 6 var lo = 0 7 var hi = nums.count - 1 8 var mid = (lo + hi) / 2 9 10 while lo <= hi { 11 mid = (lo + hi) / 2 12 13 //print("Check Piv [(lo) (mid) (hi)] => {(nums[lo]) (nums[mid]) (nums[hi])}") 14 15 if nums[mid] == target { 16 return true 17 } 18 19 if nums[mid] > nums[lo] { 20 21 if target >= nums[lo] && target < nums[mid] { 22 hi = mid - 1 23 } else { 24 lo = mid + 1 25 } 26 } else if nums[mid] < nums[lo] { 27 if target > nums[mid] && target <= nums[hi] { 28 lo = mid + 1 29 } else { 30 hi = mid - 1 31 } 32 } else { 33 lo += 1 34 } 35 } 36 return false 37 } 38 }
20ms
1 class Solution { 2 func search(_ nums: [Int], _ target: Int) -> Bool { 3 4 var left = 0, right = nums.count - 1 5 6 while left <= right { 7 let mid = left + (right - left) / 2 8 if nums[mid] == target { 9 return true 10 } 11 if nums[mid] == nums[left] { 12 left += 1 13 } else if nums[mid] > nums[left] { 14 if target >= nums[left] && target < nums[mid] { 15 right = mid - 1 16 } else { 17 left = mid + 1 18 } 19 } else { 20 if target > nums[mid] && target <= nums[right] { 21 left = mid + 1 22 } else { 23 right = mid - 1 24 } 25 } 26 } 27 28 return false 29 } 30 }
40ms
1 class Solution { 2 func search(_ nums: [Int], _ target: Int) -> Bool { 3 var set: Set = Set<Int>.init() 4 for d in nums { 5 if d == target { 6 return true 7 }else { 8 if set.contains(target) { 9 return true 10 }else { 11 set.insert(d) 12 } 13 } 14 } 15 return false 16 } 17 }
44ms
1 class Solution { 2 3 func search(_ nums: [Int], _ target: Int) -> Bool { 4 return nums.contains(target) 5 } 6 }
52ms
1 class Solution { 2 func search(_ nums: [Int], _ target: Int) -> Bool { 3 if nums.isEmpty 4 { 5 return false 6 } 7 8 var distinct = removeDuplicates(nums) 9 10 return searchRec(&distinct, target, start:0, end:distinct.count - 1) 11 } 12 13 func searchRec(_ num: inout [Int], _ target: Int, start: Int, end: Int) -> Bool 14 { 15 if start == end 16 { 17 return num[start] == target 18 } 19 20 let diff = end - start 21 let center = start + (diff - (diff % 2)) / 2 22 23 if num[center] == target 24 { 25 return true 26 } 27 28 if num[start] <= num[center] 29 { 30 if target >= num[start] && target < num[center] 31 { 32 return searchRec(&num, target, start:start, end:center - 1) 33 } 34 35 return searchRec(&num, target, start:center + 1, end:end) 36 } 37 else if num[start] >= num[center] 38 { 39 if target >= num[start] || target < num[center] 40 { 41 return searchRec(&num, target, start:start, end:center - 1) 42 } 43 44 return searchRec(&num, target, start:center + 1, end:end) 45 } 46 47 return false 48 49 } 50 51 func removeDuplicates(_ nums: [Int]) -> [Int] 52 { 53 if nums.isEmpty 54 { 55 return nums 56 } 57 58 var distinct = [nums[0]] 59 var prev = nums[0] 60 61 for val in nums[1..<nums.count] 62 { 63 if val != prev && val != nums[0] 64 { 65 distinct.append(val) 66 } 67 68 prev = val 69 } 70 71 return distinct 72 } 73 }