Find the Missing Number in an Array Using JavaScript | Interview Question Explained
In this video, we solve a classic JavaScript interview question:
Find the missing number in a sequence from 1 to n.
We go step by step and explain the logic in a beginner-friendly way using JavaScript.
Problem Explained:
You are given an array containing numbers from 1 to n, with one number missing.
Your task is to find that missing number.
Examples Covered:
Input: [1, 2, 4, 5, 6]
Output: 3
Input: [2, 3, 4, 5]
Output: 1
Input: [1, 2, 3, 4]
Output: 5
Input: []
Output: 1
Concepts Used:
• Array traversal
• Index comparison
• Edge case handling
• JavaScript loops
This question is very important for:
• JavaScript interviews
• DSA preparation
• MERN stack developers
• Freshers and beginners
If you are preparing for coding interviews, placements, or JavaScript fundamentals, this video will help you a lot.
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🧠 Notes for Video Explanation (Speak This in Video)
• The array should contain numbers from 1 to n
• Loop through the array
• Compare index plus one with the actual value
• If they don’t match, that number is missing
• If all numbers match, then the missing number is n + 1
• Handle edge cases like empty array
Key Insight:
Index always starts from 0, but numbers start from 1.
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