python simple algorithm optimization

• Computer industry famous formula, proposed by the Swiss computer scientist Jack Nicklaus. Witts (Niklaus Wirth), also won the Turing Award 
  Program = algorithm + data structure 
  not seen data structures and algorithms, sometimes face the problem may not have any idea I do not know how to start to solve; 
  most of the time might solve the problem, but the program is not running efficiency and cost awareness, poor performance; 
  sometimes help tool developed by others to solve the problem temporarily, but when it came to performance bottlenecks, and I do not know how to carry out targeted optimization * *

• Simulation scenarios 
  a, b, c three number 
  1. A + B + C = 1000 (0--1000) 
  2.a ** ** 2 = B 2 + C 2 ** 
  find a, b, c possible combinations ? ? ?

• normal

 

import time
s_time = time.time()
import datetime
starttime = datetime.datetime.now()
print(starttime)
for a in range(1,1001):
    for b in range(1,1001):
        for c in range(1, 1001):
            if a+b+c == 1000 and a**2 + b**2 == c**2:
                print("a= %s,b= %s,c= %s"% (a,b,c))
endtime = datetime.datetime.now()
yonghsi = the endtime - startTime
 Print ( " time is consumed:% S " % yonghsi)

 

• • time

• Algorithm optimization

import time
starttime = time.time()
print(starttime)
for a in range(1,1001):
    for b in range(1,1001):
        c = 1000 - a - b
        if a**2 + b**2 == c**2:
            print("a= %s,b= %s,c= %s"% (a,b,c))
endtime = time.time()
print(endtime)
Yongshi = endtime- startTime
 Print ( " total time was:% S " % Yongshi)

• • 
• timeit (python built-in test module)

Import the timeit    # Python built-in performance test module

def func():
    for a in range(1, 1001):
        for b in range(1, 1001):
            c = 1000 - a - b
            if a ** 2 + b ** 2 == c ** 2:
                print("a= %s,b= %s,c= %s" % (a, b, c))

timer01 = timeit.Timer ( " FUNC () " , " from __main__ Import FUNC " )
 # the Timer (first position you want to write performance test for which function. The second position from which to introduce this function) 
Print (timer01 .timeit (10) / 10)   # here timeit () represents the number of tests 1.2070892295 #

 

 

2020-01-07 00:08:26