Find the missing number in an array of 1 to N
Updated Apr 28, 2026
Short answer
XOR all array elements and all numbers from 1 to N.
Deep explanation
This explores bitwise arithmetic and identity properties. XOR all array elements and all numbers from 1 to N. These patterns are common in technical coding interviews.
Real-world example
Efficient memory allocation alignment checks.
Common mistakes
- Not handling the case where n = 0 for power-of-two checks.
Follow-up questions
- What is the time complexity?