Playing with fibonacci

many_fibos.dart

void main() {
  print(fibo(3));
  print(fibo(5));
  
  print(fibo(13));
  print(fibo(8));
}

// TODO: refactorizar usando cache
int fibox(int n) {
  assert(n >= 1, 'No es posible calcular fib($n)');
  int a = 1;
  int b = 1;
  for(int i = 1; i < n; i++) {
    int f = b + a;
    a = b;
    b = f;
    print('calc: $i - $f');
  }
  
  return b;
}

List<int> cache = [0, 1, 1];
int fibo(int n) {
  assert(n >= 1, 'No es posible calcular fib($n)');
  if(n < cache.length) {
    print('$n - $cache');
    return cache[n];
  }
  
  for(int i = cache.length; i <= n; i++) {
    int f = cache[i-1] + cache[i-2];
    print('calc: $i - $f');
    cache.add(f);
  }
  
  print('$n - $cache');
  return cache.last;
}

int fib(int n) {
  final cache = <int>[0, 1, 1];
  int a = _fib(n, cache);
  print('cache: $cache');
  return a;
}

int _fib(int n, List<int> cache) {
  assert(n >= 1, 'No es posible calcular fib($n)');
  
  
  if(cache.length > n){
    print('Calculando fib($n) - $cache');
    return cache[n];
  }
  
  if(cache.length == n) {
    int f = cache[n - 1] + cache[n - 2];
    cache.add(f);
    print('Calculando fib($n) - $cache');
    return f;
  }
  
  print('Calculando fib($n) - $cache');
  int f = _fib(n-1, cache) + cache[n-2];
  cache.add(f);
  return f;
}