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July 7, 2018 23:56
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Shows the differences between recursive and dynamic programming
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| int calls = 0; | |
| int i = 35; //the fibonacci number to calculate | |
| void main() { | |
| Stopwatch _timer; | |
| _timer = new Stopwatch()..start(); | |
| print('fibonacci($i) = ${recursiveFibonacci(i)} was calculated using the recursive approach. (time: ${_timer.elapsedMilliseconds} ms, calls: $calls)'); | |
| _timer.reset(); | |
| calls = 0; | |
| print('fibonacci($i) = ${dynamicFibonacci(i)} was calculated using the dynamic approach. (time: ${_timer.elapsedMilliseconds} ms, calls: $calls)'); | |
| } | |
| /// Computes the nth Fibonacci number with recursive calls. | |
| int recursiveFibonacci(int n) { | |
| calls++; | |
| return n < 2 ? n : (recursiveFibonacci(n - 1) + recursiveFibonacci(n - 2)); | |
| } | |
| /// Computes the nth Fibonacci number with dynamic programming | |
| int dynamicFibonacci(int n) { | |
| calls++; | |
| var f = [0, 1]; | |
| for (int k = 2; k <= n; k++) { | |
| calls++; | |
| f[k%2] = f[(k-1)%2] + f[(k-2)%2]; | |
| } | |
| return f[n%2]; | |
| } |
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