Search in Rotated Sorted Array II问题及解法

问题描述：

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).

Write a function to determine if a given target is in the array.

The array may contain duplicates.

问题分析：

对于查找一类问题，先考虑是否可以利用二分查找法。对于该题目，我们可以做一些适当的转化，使得查找可以遵循二分查找算法。

过程详见代码：

class Solution {public:    bool search(vector<int>& nums, int target) {        if (nums.empty()) return false;int left = 0;int right = nums.size() - 1;int mid;while (left < right){mid = left + (right - left) / 2;if (nums[mid] == target) return true;if (nums[mid] < nums[right]){if (nums[mid] < target && target <= nums[right]) left = mid + 1;else right = mid;}else if (nums[mid] > nums[right]){if (nums[mid] > target && target >= nums[left]) right = mid;else left = mid + 1;}else right--;}return nums[left] == target;    }};