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Single Number

Explore how to identify the single number in an integer array where every other element appears twice. Learn to apply bitwise operations for a solution that runs in linear time and uses constant space, enhancing your coding interview problem-solving skills.

Statement

Given an array of integers, where every element appears twice except for one, find the element that occurs only once.

Note: The solution must have linear runtime and constant space complexity.

Constraints:

  • 11 \leq nums.length 103\leq 10^3
  • 3×103-3 \times 10^3 \leq nums[i] 3×103\leq 3 \times 10^3

Example

Understand the problem

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

Single Number

1.

From the given array of integers, find the number that appears once.

array = [1, 2, 4, 1, 2, 4, 9, 6, 7, 6, 7]

A.

1

B.

2

C.

9

D.

6


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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
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Try it yourself

Implement your solution in the following coding playground:

Python
usercode > main.py
def single_number(nums):
# Replace this placeholder return statement with your code
return -1
Single Number