When tackling data structures and algorithms (DSA) problems, whether in technical interviews or competitive programming, engineers often overlook the most critical piece of data: problem constraints. While the problem description explains what to do, the constraints dictate how to do it.
Paying attention to constraints eliminates guesswork, preventing you from wasting time on algorithms that are destined to fail.
We will use practical examples to showcase how constraints make or break a solution.
The Foundation: The 10^9 Operations Rule
Online judges (such as LeetCode, HackerRank, or Codeforces) impose strict execution time limits, typically around 1.0 to 2.0 seconds per test case. As a general rule of thumb, when using Big O notation:
