33. Search in Rotated Sorted Array
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]).
You are given a target value to search. If found in the array return its index, otherwise return -1.
You may assume no duplicate exists in the array.
Your algorithm's runtime complexity must be in the order of O(log n).
Example 1:
代码语言：javascript复制Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4Example 2:
代码语言：javascript复制Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1思路：
题目意思是找出一个翻转过的数组中目标元素的下标，使用binary search来做，根据最左边和中间的元素来区分中间元素的左边是翻转过的还是没有翻转过的。
代码：
go：
代码语言：javascript复制func search(nums []int, target int) int {
if nums == nil || len(nums) == 0 {
return -1
}
left := 0
right := len(nums)-1
for left <= right {
mid := left (right - left) / 2
if nums[mid] == target {
return mid
} else if nums[mid] < nums[left] {
// 左边是rotated sorted array
if target > nums[mid] && target <= nums[right] {
left = mid 1
} else {
right = mid - 1
}
} else {
// 右边是rotated sorted array 左边是sorted array
if target < nums[mid] && target >= nums[left] {
right = mid - 1
} else {
left = mid 1;
}
}
}
return -1
}
