Search in Rotated Sorted Array II

<-M 81> Search in Rotated Sorted Array II

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