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Single Element in a Sorted Array

Explore how to apply modified binary search to locate the single element that appears once in a sorted array where all other elements appear twice. Understand constraints and implement a solution with O(log n) time and O(1) space complexity.

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Statement

You are given a sorted array of integers, nums, where all integers appear twice except for one. Your task is to find and return the single integer that appears only once.

The solution should have a time complexity of O(log⁡n)O(\log n) or better and a space complexity of O(1)O(1).

Constraints:

  • 1≤1 \leq nums.length ≤103\leq 10^3

  • 0≤0 \leq nums[i] ≤103\leq 10^3

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps us to check if you’re solving the correct problem:

Single Element in a Sorted Array

1.

What is the output if the following array is provided as input?

[1, 1, 2, 2, 3, 4, 4]

A.

1

B.

3

C.

2

D.

4

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in the following coding playground:

Java
usercode > SingleElement.java
import java.util.*;
public class SingleElement{
   public static int singleNonDuplicate(int[] nums) {
      
      // Replace this placeholder return statement with your code
      return 0;
   }
}
Single Element in a Sorted Array