Integer Overflow in Missing Number CalculationLocation

[yashi-here]

missing_number.cpp Issue:
The code uses int to store the sum of numbers, which will overflow for large inputs.

Analysis: The mathematical formula for the sum of the first $n$ numbers is $\frac{n(n+1)}{2}$. If $n = 100,000$, the calculation $100,000 \times 100,001$ results in approximately 10 billion. Since a standard 32-bit int in C++ can only hold up to 2.1 billion, the value will overflow, wrap around to a negative number, and produce a completely incorrect result.

Impact: The program will fail standard competitive programming test cases where $n$ is large.