LeetCode 75 C++ | Step-by-Step Solutions (LAN Academy) - LeetCode 724 – Find Pivot Index | C++ Prefix Sum Trick

In this video we solve LeetCode 724 – Find Pivot Index in C++ using a clean and efficient prefix sum trick. The pivot index is the position where the sum of all numbers to the left is equal to the sum of all numbers to the right. Instead of using nested loops (O(n²)), we use a simple linear-time approach: 1️⃣ Compute the total sum of the array 2️⃣ Walk through the array once, keeping track of the left sum 3️⃣ At each position, check if leftSum == totalSum - leftSum - nums[i] 4️⃣ Return the first index that satisfies the condition (or -1 if none do) What you’ll learn in this video: - How to translate the problem statement into equations - How prefix sums help you avoid unnecessary loops - A clear step-by-step C++ implementation - Time and space complexity analysis (O(n) time, O(1) extra space) ⏱️ Timestamps: 00:00 – Problem explanation and examples 02:00 – Naive approach vs. prefix sum idea 04:00 – Deriving the pivot condition 06:00 – Coding the C++ solution step-by-step 11:00 – Complexity analysis and edge cases 12:00 – Recap and next suggested problems This problem is great for: - Practicing array and prefix sum techniques - Building intuition for sum-based interview problems - Strengthening your C++ fundamentals Follow LAN Academy Website: https://lanacademy-school.thinkific.com YouTube: @lanacademy9521 Twitter: https://x.com/SolutionsLan If this video helps you: 👍 Like the video 💬 Comment which problem you want next 🔔 Subscribe to the channel for more C++ and algorithms tutorials! @reper #foryou #viral #reper #urmaritori #for