python_para_desenvolvedores_2ed

Performance 279
"""
Fibonacci calculado por um loop.
"""
if n > 1:
# O dicionário guarda os resultados
fibs = {0:1, 1:1}
for i in xrange(2, n + 1):
fibs[i] = fibs[i - 1] + fibs[i - 2]
return fibs[n]
else:
return 1
print 'fib1'
cProfile.run('[fib1(x) for x in xrange(1, 31)]')
print 'fib2'
cProfile.run('[fib2(x) for x in xrange(1, 31)]')
Saída:
fib1
7049124 function calls (32 primitive calls) in 21.844 CPU seconds
Ordered by: standard name
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 21.844 21.844 <string>:1(<module>)
7049122/30 21.844 0.000 21.844 0.728 fibs.py:4(fib1)
1 0.000 0.000 0.000 0.000 {method 'disable' of
'_lsprof.Profiler' objects}
fib2
32 function calls in 0.001 CPU seconds
Ordered by: standard name
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 0.001 0.001 <string>:1(<module>)
30 0.001 0.000 0.001 0.000 fibs.py:13(fib2)
1 0.000 0.000 0.000 0.000 {method 'disable' of
'_lsprof.Profiler' objects}
A performance do cálculo da série de Fibonacci usando um laço que preenche