[Swift]LeetCode153. 寻找旋转排序数组中的最小值 | Find Minimum in Rotated Sorted Array

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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e.,  [0,1,2,4,5,6,7] might become  [4,5,6,7,0,1,2]).

Find the minimum element.

You may assume no duplicate exists in the array.

Example 1:

Input: [3,4,5,1,2] 
Output: 1

Example 2:

Input: [4,5,6,7,0,1,2]
Output: 0

---

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 [0,1,2,4,5,6,7] 可能变为 [4,5,6,7,0,1,2] )。

请找出其中最小的元素。

你可以假设数组中不存在重复元素。

示例 1:

输入: [3,4,5,1,2]
输出: 1

示例 2:

输入: [4,5,6,7,0,1,2]
输出: 0

---

12ms

class Solution {
    func findMin(_ nums: [Int]) -> Int {
        if nums.count == 0 {
            return 0
        }

        var left = 0
        var right = nums.count - 1

        while left < right {
            let middle = left + (right - left) / 2
            if nums[middle] > nums[right] {
                left = middle + 1
            } else {
                right = middle
            }
        }

        return nums[left]
    }
}

---

16ms

class Solution {
    func findMin(_ nums: [Int]) -> Int {
        
        if nums.count == 1{
            return nums[0]
        }

            if nums[0] > nums[nums.count-1]{
                for i in 0..<(nums.count-1){
                    if nums[i] > nums[i+1] {
                        return nums[i+1]
                    } 
                }
            }else{
                return nums[0]
            }
            
        return -1
    }
}

---

24ms

class Solution {
    
    func findMin(_ nums: [Int]) -> Int {
        var start = 0
        var end = nums.count - 1
        
        while start < end {
            if nums[start] < nums[end] {
                return nums[start]
            }
            
            var mid = (start + end) / 2
            
            if nums[mid] >= nums[start] {
                start = mid + 1
            }else {
                end = mid
            }
        }
        
        return nums[start]
    }
    
    func findMin2(_ nums: [Int]) -> Int {
        for i in 1 ..< nums.count {
            if nums[i] < nums [i-1]{
                return nums[i]
            }
        }
        
        return nums[0]
    }
}

---

28ms

class Solution {
  func findMin(_ nums: [Int]) -> Int {
    var start = 0
    var end = nums.count - 1
    var gap = (end - start) / 2
    while (end - start) > 1 {
      if nums[gap] > nums[end] {
        start = gap
        gap = start + ((end - gap) / 2)
      }else if nums[gap] < nums[end]{
        end = gap
        gap = (end - start) / 2
      }
    }
    return nums[end] > nums[start] ? nums[start] : nums[end]
  }
}