⚡️ Speed up function fibonacci by 15.63%#314
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The recursive `fibonacci` function was replaced with an iterative bottom-up approach that tracks only the two most recent values (`prev2`, `prev1`) in a single forward pass, eliminating the exponential call tree that recomputes the same subproblems thousands of times. For example, computing `fibonacci(18)` originally requires ~4,000+ recursive calls with deep stack overhead, while the optimized version completes in exactly 17 loop iterations with O(1) space. This yields a 15% runtime improvement across the test suite, which exercises inputs from 0 to 18, with no correctness regressions.
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📄 15.63% (0.16x) speedup for
fibonacciinsrc/algorithms/dynamic_programming.py⏱️ Runtime :
8.93 milliseconds→7.72 milliseconds(best of161runs)📝 Explanation and details
The recursive
fibonaccifunction was replaced with an iterative bottom-up approach that tracks only the two most recent values (prev2,prev1) in a single forward pass, eliminating the exponential call tree that recomputes the same subproblems thousands of times. For example, computingfibonacci(18)originally requires ~4,000+ recursive calls with deep stack overhead, while the optimized version completes in exactly 17 loop iterations with O(1) space. This yields a 15% runtime improvement across the test suite, which exercises inputs from 0 to 18, with no correctness regressions.✅ Correctness verification report:
To edit these changes
git checkout codeflash/optimize-fibonacci-mo973r8dand push.