import time
from itertools import product
def with_nested_loop():
s = 0
for i in range(5000):
for j in range(5000):
s += i / (j + 1)
print(s)
def with_product():
s = 0
for i, j in product(range(5000), range(5000)):
s += i / (j + 1)
print(s)
start = time.time()
with_nested_loop()
elapsed = time.time() - start
print('{:.6f} sec'.format(elapsed))
start = time.time()
with_product()
elapsed = time.time() - start
print('{:.6f} sec'.format(elapsed))
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