Two Pointer Technique Beats Nested Loops in Two Sum II

🚀 Efficiency Wins: Why Two Pointers Beat Nested Loops 👈👉 Today’s deep dive into the Two Pointer Technique was a perfect reminder that "thinking before coding" is a developer's best skill. Here is how I optimized my approach to solving Two Sum II: 🛠️ Key Technical Takeaways Kill Redundant Flags: I initially used a while(!flag) setup. I quickly realized this was extra baggage—using while (left < right) is the cleaner, more idiomatic "guardrail" that naturally prevents infinite loops. The 1-Indexed Challenge: The problem requires a 1-indexed return. I learned to handle the logic in 0-index but adjust the final output by adding 1 to avoid off-by-one errors. The "Not Found" Safety Net: If no pair exists, returning [-1, -1] is the standard way to signal "not found." Without the left < right condition, the code could crash or loop forever if the target isn't present. ⚡ The Efficiency Edge O(n) vs O(n²): Instead of checking every possible pair (slow), we use two "bookmarks" and find the answer in a single pass. Space Efficiency: By using only two variables, the space complexity stays O(1), no matter how massive the dataset. 🏆 The Milestone Successfully solved Two Sum II using a clean, linear approach! Moving from brute-force to optimized logic feels like a massive level-up. 💻 Code Snippet: function two_pointers(input, target){ let left = 0 let right = input.length - 1 while(left < right){ const currentSum = input[left] + input[right] if(currentSum === target){ return [left + 1, right + 1] } else if(currentSum > target){ right -= 1 } else{ left += 1 } } return [-1, -1] } let input = [2, 7, 11, 15] let target = 9 console.log(two_pointers(input, target)) #DataStructures #Algorithms #LeetCode #CodingInterviews #CleanCode #JavaScript #SoftwareEngineering #ProblemSolving

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