# Single Element in a Sorted Array

Easy
0/40
Average time to solve is 15m
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## Problem statement

You are given a sorted array ‘arr’ of ‘n’ numbers such that every number occurred twice in the array except one, which appears only once.

Return the number that appears once.

Example:
``````Input: 'arr' = [1,1,2,2,4,5,5]

Output: 4

Explanation:
Number 4 only appears once the array.
``````

Note :
``````Exactly one number in the array 'arr' appears once.
``````

Detailed explanation ( Input/output format, Notes, Images )
##### Sample Input 1 :
``````5
1 1 3 5 5
``````

##### Sample Output 1 :
``````3
``````

##### Explanation of Sample Input 1 :
``````Given array is [1, 1, 3, 5, 5]
Here, 3 occurs once in the array. So, the answer is 3.
``````

##### Sample Input 2 :
``````5
1 1 4 4 15
``````

##### Sample Output 2 :
``````15
``````

##### Explanation of Sample Input 2 :
``````The array is [1, 1, 4, 4, 15].
Here, 15 occurs once in the array. So, the answer is 15.
``````

##### Expected Time Complexity:
``````Try to solve this in O(log(n)).
``````

##### Constraints :
``````1 <= n <= 10^5
0 <= arr[i] <= 10^9

Time Limit: 1 sec
``````
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