⚡️ Speed up method Algorithms.fibonacci by 15%

[codeflash-ai]

📄 15% (0.15x) speedup for Algorithms.fibonacci in code_to_optimize/java/src/main/java/com/example/Algorithms.java

⏱️ Runtime : 1.17 milliseconds → 1.01 milliseconds (best of 5 runs)

📝 Explanation and details

The optimized code achieves a 15% runtime improvement by replacing the exponentially complex recursive Fibonacci implementation with an iterative approach.

Key Performance Optimization:

The original recursive implementation suffers from exponential time complexity O(2^n) because it recalculates the same Fibonacci values repeatedly. For example, calculating fibonacci(5) triggers calls to fibonacci(4) and fibonacci(3), but fibonacci(4) also calls fibonacci(3), resulting in redundant computation that grows exponentially.

The optimized version uses iterative computation with O(n) time complexity. It maintains just two variables (prev and curr) to track consecutive Fibonacci numbers, computing each value exactly once through a simple loop. This eliminates all redundant function calls and stack overhead.

Why This Improves Runtime:

1. No redundant calculations: Each Fibonacci number is computed exactly once instead of exponentially many times
2. No function call overhead: Eliminates the cost of recursive function calls and stack frame management
3. Better cache locality: Sequential loop iterations have superior memory access patterns compared to scattered recursive calls
4. Constant space usage: Uses O(1) space instead of O(n) stack depth from recursion

The 15% improvement shown here is actually conservative - the speedup becomes dramatically more significant as n increases. For small values of n (likely used in these tests), the benefit is modest, but for n=30+, the iterative version would be orders of magnitude faster as the recursive version's exponential complexity dominates.

This optimization is especially valuable if the Fibonacci function is called frequently or with larger input values in production workloads.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	✅ 256 Passed
🌀 Generated Regression Tests	✅ 1344 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

⚙️ Click to see Existing Unit Tests

🌀 Click to see Generated Regression Tests

To edit these changes git checkout codeflash/optimize-Algorithms.fibonacci-mlbitzag and push.