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oheyandy
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import time | |
bound,mem = 1000000,{} | |
def collatz(n): | |
if n==1: return [1] | |
else: return [n] + collatz(n/2 if (n%2==0) else 3*n+1) if (n>1) else [1] | |
def collatzCount_recursive_memoized(n): | |
if n not in mem: mem[n]= 1 + collatzCount_recursive_memoized(n/2 if (n%2==0) else 3*n+1) if (n>1) else 1 | |
return mem[n] | |
def collatzCount_iterative(n): | |
count = 1 | |
if n ==1: | |
return count | |
while n !=1: | |
if n%2 == 0: | |
count +=1 | |
n = n/2 | |
else: | |
count +=1 | |
n = (n*3) + 1 | |
return count | |
iterative_mem = {} | |
iterative_mem[1] = 1 | |
def collatzCount_iterative_memoized(n): | |
count = 1 | |
initial_n = n | |
while n not in iterative_mem: | |
if n%2 == 0: | |
count +=1 | |
n = n/2 | |
else: | |
count +=1 | |
n = (n*3) + 1 | |
iterative_mem[initial_n] = count + iterative_mem[n] | |
return iterative_mem[initial_n] | |
iterative_mem_pedantic = {} | |
iterative_mem_pedantic[1] = 1 | |
def collatzCount_iterative_memoized_pedantic(n): | |
count = 1 | |
initial_n = n | |
while not iterative_mem_pedantic.get(n,False): | |
if n%2 == 0: | |
count +=1 | |
n = n/2 | |
else: | |
count +=1 | |
n = (n*3) + 1 | |
iterative_mem_pedantic[initial_n] = count + iterative_mem_pedantic[n] | |
return iterative_mem_pedantic[initial_n] | |
iterative_mem_pedantic_without_dot = {} | |
iterative_mem_pedantic_without_dot[1] = 1 | |
get_direct = iterative_mem_pedantic_without_dot.get | |
def collatzCount_iterative_memoized_pedantic_without_dot(n): | |
count = 1 | |
initial_n = n | |
while not get_direct(n,False): | |
if n%2 == 0: | |
count +=1 | |
n = n/2 | |
else: | |
count +=1 | |
n = (n*3) + 1 | |
iterative_mem_pedantic_without_dot[initial_n] = count + iterative_mem_pedantic_without_dot[n] | |
return iterative_mem_pedantic_without_dot[initial_n] | |
def test(f,bound,number_of_runs): | |
total_time = 0 | |
for i in range(number_of_runs): | |
total_time += single_time(f,bound) | |
print total_time/number_of_runs,"for",f.__name__ | |
def single_time(f,bound): | |
time1 = time.time() | |
biggest_sequence = len(collatz(max(((i,f(i)) for i in xrange(1,bound)),key=lambda x: x[1])[0])) | |
print biggest_sequence | |
return time.time()-time1 | |
#test(collatzCount_recursive_memoized,10**4,10) | |
#test(collatzCount_iterative,10**4,10) | |
test(collatzCount_iterative_memoized,10**4,10) | |
test(collatzCount_iterative_memoized_pedantic,10**4,10) | |
test(collatzCount_iterative_memoized_pedantic_without_dot,10**4,10) |
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guess there's just too much overhead in a while loop versus recursive calls. Did not expect that.