Solving Missing Number using Math.

Problem

Solve Missing Number.

Pattern

This problem demonstrates the Math pattern.

Approach

Apply mathematical logic.

Solution 

  // solution

Complexity

O(n)

Best Practices

  • Identify the pattern before coding — pattern recognition saves time
  • Handle edge cases: empty input, single element, duplicates
  • Use descriptive variable names even in timed interviews
  • Test with the provided examples plus one custom case