Python可以比C++更快，你不信？
菜鸟学Python
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·
2021-04-03 20:13
from numba import jit
import random
@jit(nopython=True)
def monte_carlo_pi(nsamples):
acc = 0
for i in range(nsamples):
x = random.random()
y = random.random()
if (x ** 2 + y ** 2) < 1.0:
acc += 1
return 4.0 * acc / nsamples
@numba.jit(nopython=True, parallel=True)
def logistic_regression(Y, X, w, iterations):
for i in range(iterations):
w -= np.dot(((1.0 /
(1.0 + np.exp(-Y * np.dot(X, w)))
- 1.0) * Y), X)
return w
import math
import time
def is_prime(num):
if num == 2:
return True
if num <= 1 or not num % 2:
return False
for div in range(3, int(math.sqrt(num) + 1), 2):
if not num % div:
return False
return True
def run_program(N):
total = 0
for i in range(N):
if is_prime(i):
total += 1
return total
if __name__ == "__main__":
N = 10000000
start = time.time()
total = run_program(N)
end = time.time()
print(f"total prime num is {total}")
print(f"cost {end - start}s")
total prime num is 664579
cost 47.386465072631836s
#include <iostream>
#include <cmath>
#include <time.h>
using namespace std;
bool isPrime(int num) {
if (num == 2) return true;
if (num <= 1 || num % 2 == 0) return false;
double sqrt_num = sqrt(double(num));
for (int div = 3; div <= sqrt_num; div +=2){
if (num % div == 0) return false;
}
return true;
}
int run_program(int N){
int total = 0;
for (int i; i < N; i++) {
if(isPrime(i)) total ++;
}
return total;
}
int main()
{
int N = 10000000;
clock_t start,end;
start = clock();
int total = run_program(N);
end = clock();
cout << "total prime num is " << total;
cout << "\ncost " << (end - start) / ((double) CLOCKS_PER_SEC) << "s\n";
return 0;
}
$ g++ isPrime.cpp -o isPrime
$ ./isPrime
total prime num is 664579
cost 2.36221s
import math
import time
from numba import njit
# @njit 相当于 @jit(nopython=True)
@njit
def is_prime(num):
if num == 2:
return True
if num <= 1 or not num % 2:
return False
for div in range(3, int(math.sqrt(num) + 1), 2):
if not num % div:
return False
return True
@njit
def run_program(N):
total = 0
for i in range(N):
if is_prime(i):
total += 1
return total
if __name__ == "__main__":
N = 10000000
start = time.time()
total = run_program(N)
end = time.time()
print(f"total prime num is {total}")
print(f"cost {end - start}s")
total prime num is 664579
cost 3.0948808193206787s
import math
import time
from numba import njit, prange
@njit
def is_prime(num):
if num == 2:
return True
if num <= 1 or not num % 2:
return False
for div in range(3, int(math.sqrt(num) + 1), 2):
if not num % div:
return False
return True
@njit(parallel = True)
def run_program(N):
total = 0
for i in prange(N):
if is_prime(i):
total += 1
return total
if __name__ == "__main__":
N = 10000000
start = time.time()
total = run_program(N)
end = time.time()
print(f"total prime num is {total}")
print(f"cost {end - start}s")
python isPrime.py
total prime num is 664579
cost 1.4398791790008545s
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