81. Search in Rotated Sorted Array II
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题目
Follow up for “Search in Rotated Sorted Array”:
What if duplicates are allowed?
Would this affect the run-time complexity? How and why?
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.
思路
这道题目,如果仅仅是实现,是很简单的,最坏情况O(n),我们知道在有序数组的情况下,二分搜索的时间复杂度是O(logn),那么在存在反转的情况下,能否使用二分搜索呢?答案是肯定的,唯一的区别就是三个索引值确定需要修改:left,right,mid
代码
class Solution {public: bool search(vector<int>& nums, int target) { if(nums.empty()) return false; int l=0,r=nums.size()-1; int mid = 0; while(l<r) { mid = (l+r)/2; if(nums[mid]==target)//如果相等 return true; if(nums[mid]>nums[r])//如果大于 { if(nums[mid]>target&&nums[l]<=target) r=mid-1; else l=mid+1; } else if(nums[mid]<nums[r])//如果小于 { if(nums[mid]<target&&nums[r]>=target) l=mid+1; else r=mid-1; } else //如果等于 r--; } return nums[l]==target?true:false; }};
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- 81.Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
- 81. Search in Rotated Sorted Array II
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