19.2.19 [LeetCode 81] Search in Rotated Sorted Array II

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

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

You are given a target value to search. If found in the array return true, otherwise return false.

Example 1:

Input: nums = [2,5,6,0,0,1,2], target = 0
Output: true

Example 2:

Input: nums = [2,5,6,0,0,1,2], target = 3
Output: false

Follow up:

  • This is a follow up problem to Search in Rotated Sorted Array, where nums may contain duplicates.
  • Would this affect the run-time complexity? How and why?
 1 class Solution {
 2 public:
 3     bool search(vector<int>& nums, int target) {
 4         if (nums.empty())return false;
 5         int pivot = nums[0], n = nums.size(), s = 0, e = n - 1;
 6         while (e>=s && nums[e] == pivot)
 7             e--;
 8         if (e < s)return pivot == target;
 9         while (s <= e) {
10             int mid = (s + e) / 2;
11             if (nums[mid] >= pivot)
12                 s = mid + 1;
13             else
14                 e = mid - 1;
15         }
16         int mididx = e, S, E;
17         if (pivot > target)
18             S = mididx + 1, E = n - 1;
19         else
20             S = 0, E = mididx;
21         while (S <= E) {
22             int mid = (S + E) / 2;
23             if (nums[mid] < target)
24                 S = mid + 1;
25             else if (nums[mid] == target)return true;
26             else E = mid - 1;
27         }
28         return false;
29     }
30 };
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posted @ 2019-02-19 09:28  TobicYAL  阅读(141)  评论(0)  编辑  收藏  举报