can u solve this question? with bit manipulation in constant extra space and linear time complexity
▎Title: 137. Single Number II

Difficulty: Medium

Denoscription:

Given an integer array nums where every element appears three times except for one, which appears exactly once, find the single element and return it.

You must implement a solution with a linear runtime complexity and use only constant extra space.

Example 1:
Input: nums = [2,2,3,2]
Output: 3

Example 2:
Input: nums = [0,1,0,1,0,1,99]
Output: 99

Constraints:

• 1 <= nums.length <= 3 * 10^4

• -2^31 <= nums[i] <= 2^31 - 1

• Each element in nums appears exactly three times except for one element which appears once.

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The 10th Ethiopian Collegiate Programming Contest (ETCPC 2025) is officially accepting team registrations. This is your opportunity to represent Addis Ababa University in Ethiopia's most prestigious coding competition.

Competition Details:

📅 Date: August 3–4, 2025
⏳ Registration Deadline: Sunday, Midnight 12:00 AM
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🧠 INSA Summer Camp Past Questions — Test Your Logic!
1️⃣ Family Logic
Given:
+ = husband
/ = sister
× = son
- = wife

What does W × Y / Z mean?
A) Son of Z's brother
B) Son of Z's sister
C) Daughter of Z's sister
D) Daughter of Z's sister

2️⃣ Code Puzzle

A girl student sleeps → Vtp htj 1

A priest teaches tonight → Vxp wyz 2

A queen speaks tonight → Tsp wyz 1

"A lady speaks tonight"?
A) Vtp Tsp
B) Tsp Wyz
C) Wyz 2 htj
D) Tsp Wyz 1

3️⃣ Word Match

Imaginative Dynamic Learning = Sue Deb Can

Complex Dynamic System = Sue Rob Be

Complex Revolutionary Thinking = Mol De Be

What is Sue Be?
A) Revolutionary System
B) Dynamic System
C) Complex Dynamic
D) Imaginative Learning

👇👇👇
Answers:
1️⃣ B
2️⃣ D
3️⃣ C

🔥 Comment your score! More coming soon.

Guys, have you heard of the BIT (Binary Indexed Tree)?
I learned about it a few days ago — it transforms both prefix‐sum queries and point updates from O(n) down to O(log n)!

In problems with frequent range‐sum queries and multiple updates, a simple prefix‐sum array fails (you’ll hit TLE). BIT handles every query and update in O(log n) time, so even with many operations your total cost stays around O(n log n) instead of O(n²).

Give it a try next time you see “range‑sum with updates”!
s
if u want to know more about it give me thumbs up i will share some questions that can be solved with with this algo with a video explanation about the topic

this is typical BIT quesiton start with this, i will add more
Range Sum

I know this one is a little bit harder question — I don’t expect you to get the solution right away.
But I’m sharing it because trying to solve this will help you deeply understand the Binary Indexed Tree (BIT) concept.

You might not get it in one go — and that’s okay.
You can refer to this video after you’ve tried solving it yourself:
🔗 Problem: Create Sorted Array through Instructions
🎥 Helpful video/Ans: YouTube Explanation

Once you solve this, you’ll be confident with how BIT works in real problems — from prefix sums to range frequency queries.

i am trying it out and it seems interesting

interview mode🤓

Check this website to practice for the INSA test. There are some rumors that INSA takes questions from this site.
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I'll share any new info as soon as I get it!