33.搜索旋转排序数组

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int n = (int)nums.size();
        if (!n) {
            return -1;
        }
        if (n == 1) {
            return nums[0] == target ? 0 : -1;
        }
        int l = 0, r = n - 1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (nums[mid] == target) return mid;
            //[0,mid]区间有序
            if (nums[0] <= nums[mid]) {
            	//target在[0,mid)区间
                if (nums[0] <= target && target < nums[mid]) {
                    r = mid - 1;
                } else {
                    l = mid + 1;
                }
            } else {
            //[0,mid]区间不是有序
                if (nums[mid] < target && target <= nums[n - 1]) {
                    //target在[mid+1,n-1]区间
                    l = mid + 1;
                } else {
                	//target在[0,mid-1]区间
                    r = mid - 1;
                }
            }
        }
        return -1;
    }
};