I wrote a simple code to compare the speed of Python vs. C++. Here is the Python code:
def count_permutations(N:int)->int:
count=0
for p in itertools.permutations(range(1,N+1)):
count += 1
return count
And here is the C++ code:
int count_permutations(int N) {
vector<int> v(N);
iota(v.begin(), v.end(), 1); // fill the vector with 1,...,N
int count=0;
do {
++count;
} while ( next_permutation(v.begin(),v.end()) );
return count;
}
When I run with Python 3.8.5 on Ubuntu, I get:
Permutations of 1..11:
39916800 permutations calculated in 3.31172251701355 seconds
Permutations of 1..12:
479001600 permutations calculated in 40.63520336151123 seconds
When I run with C++ (clang++-9) on the same Ubuntu, I get:
Permutations of 1..11:
39916800 permutations calculated in 5 seconds
Permutations of 1..12:
479001600 permutations calculated in 57 seconds
I find this very strange, since in the benchmarks website, C++ is always faster than Python.
Is it possible that recent versions of Python have become so fast that they are now faster than their C++ parallel?