Find the Unique Number
Easy
Given an array of integers where every element appears twice except for one element which appears only once, find and return the unique element.
Example
- Input:
[4, 1, 2, 1, 2] - Output:
4
Example 1
Input
[ 2, 3, 2, 4, 4 ]
Output
3
Explanation. In the array, the number 3 is the only element that appears once.
Example 2
Input
[ 7, 7, 8 ]
Output
8
Explanation. 8 appears only once, while 7 appears twice.
Example 3
Input
[ 1, 1, 2, 2, 3, 3, 4, 6, 6 ]
Output
4
Explanation. All numbers except for 4 appear twice.
Example 4
Input
[ 10, 20, 20 ]
Output
10
Explanation. 10 appears only once, while 20 appears twice.
Follow-up: How would you modify your solution if there are multiple unique numbers and you have to return them in an array?
Constraints:
The array will always contain at least three elements, ensuring there is one unique number.
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