Top 150 InterviewEasy

Missing Number

Detailed guide and Python implementation for the 'Missing Number' problem.

Problem Statement

Easy

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Write a function missingNumber(nums: List[int]) -> int.

Constraints
  • n == len(nums)
  • 1 <= n <= 10^4
  • 0 <= nums[i] <= n
  • All the numbers of nums are unique

Examples

Example 1
Input
nums = [3,0,1]
Output
2
Explanation

n = 3, range [0,3]. 2 is missing.

Example 2
Input
nums = [0,1]
Output
2
Explanation

n = 2, range [0,2]. 2 is missing.

Example 3
Input
nums = [9,6,4,2,3,5,7,0,1]
Output
8
Explanation

n = 9, range [0,9]. 8 is missing.

Need a Hint?
Consider using Bit Manipulation-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

Ready to Solve?

Open the problem in PyRun's browser-based Python editor. Your code runs fully offline — no server required.

Open in Editor

Recommended Python Resources

Expand your knowledge with related interactive tutorials, cheat sheets, and code comparisons.