154. Find Minimum in Rotated Sorted Array II

Hard

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]).

Find the minimum element.

The array may contain duplicates.

Example 1:

Input: [1,3,5]
Output: 1

Example 2:

Input: [2,2,2,0,1]
Output: 0

 1 class Solution {
 2 public:
 3     int findMin(vector<int>& a) {
 4         int low = 0;
 5         int high = a.size() -1 ;
 6         if(high==0) return a[0];
 7         int mid = low + (high - low) / 2;
 8         if (a[low]<a[high]) return a[low];
 9         while(low<high) {
10             mid = low + (high - low) / 2;
11             if (mid ==low ) break; 
12             if(a[low] < a[mid]) {  //right is shift
13                 if(a[mid]<=a[high]) return a[low];
14                 low = mid;
15             } else if (a[low] > a[mid]) {  //left is shift
16                 high =  mid;
17             } else {
18                 low++; 
19             }          
20         }
21         return a[low+1];
22     }
23 };