有没有办法测量这个算法解决这个 Soduku 拼图所花费的时间？

Posted 2023-02-22

【中文标题】有没有办法测量这个算法解决这个 Soduku 拼图所花费的时间？

【英文标题】：Is there a way to measure the time taken this algorithm takes to solve this Soduku Puzzle?

【发布时间】：2021-03-15 10:35:55

【问题描述】：

我有代码可以使用回溯算法解决数独难题。我想知道回溯算法使用 python 语言在几秒或几毫秒内解决数独难题需要多长时间。

我的代码是 '''

from tabulate import tabulate
import timeit

# A 9x9 matrix which represents our sudoku solver
sudoku_board = [
    [0,0,0,0,0,0,2,0,0],
    [0,8,0,0,0,7,0,9,0],
    [6,0,2,0,0,0,5,0,0],
    [0,7,0,0,6,0,0,0,0],
    [0,0,0,9,0,1,0,0,0],
    [0,0,0,0,2,0,0,4,0],
    [0,0,5,0,0,0,6,0,3],
    [0,9,0,4,0,0,0,7,0],
    [0,0,6,0,0,0,0,0,0]
]

# Display the board
def display_board(sudoku_board):
    print(tabulate(sudoku_board, tablefmt='fancy_grid'))


#Look for an unassigned cell if it exists return row and col values else return False
def empty_cells_exist():
    for i in range(9):
        for j in range(9):
            if sudoku_board[i][j] == 0:
                return [i, j]
    return False

# Is our choice good or not?
def valid_number_check(num, i, j):
    #Checking vertically
    for row in range(9):
        if sudoku_board[row][j] == num:
            return False

#Checking horizontally
for col in range(9):
    if sudoku_board[i][col] == num:
        return False

#Check in the 3x3 gird / box
grid_row = (i // 3) * 3
grid_col = (j // 3) * 3

for i in range(3):
    for j in range(3):
        if sudoku_board[grid_row + i][grid_col + j] == num:
            return False

# Once all tests are passed return true
return True

# Solver
def solver():
    cells_exist = empty_cells_exist()

if not cells_exist:
    return True

i, j = cells_exist[0], cells_exist[1]
for num in range(1,10):
    if valid_number_check(num, i, j):
        sudoku_board[i][j] = num
       
        #Backtracking (checking the next step)
        if solver():
            return True
        else:
            sudoku_board[i][j] = 0
            
#     False if nothing (1 through 9) yield an "accepted answer"
    return False



    display_board(sudoku_board)

    if solver():
        display_board(sudoku_board)
    else:
        print("no solution available")

    if __name__ == "__main__":
         print(timeit.timeit(solver,number=10000))

,,,

如您所见，我尝试为求解器函数计时，但它返回的数字类似于 0.07027392299999846，这不是所需的格式。我要求它以清晰易读的格式供人类理解。比如分秒格式。

【问题讨论】：

您可以在文档中阅读它，它以秒为单位。请参阅：docs.python.org/3/library/timeit.html。它与您认为需要多长时间一致吗？注意：“默认情况下，timeit() 在计时期间会暂时关闭垃圾收集。这种做法的优点是它使独立计时更具可比性。缺点是GC可能是被测函数性能的重要组成部分. 如果是这样，GC 可以作为设置字符串中的第一条语句重新启用。”详情见链接。

【参考方案1】：

为此，我通常使用datetime.datetime.now：

>>> import datetime
>>> begin = datetime.datetime.now()
>>> begin
datetime.datetime(2021, 3, 15, ..., 40, 14, 560666)
>>> end = datetime.datetime.now()
>>> end - begin
datetime.timedelta(seconds=10, microseconds=530067)
>>> str(_)
'0:00:10.530067' # the nice representation

或者自己构造timedelta object：

>>> datetime.timedelta(seconds=0.07027392299999846)
datetime.timedelta(microseconds=70274)
>>> str(_)
'0:00:00.070274'

所以您的代码可能如下所示：

dt = timeit.timeit(solver,number=10000)
print(datetime.timedelta(seconds=dt))

【参考方案2】：

您可以使用模块时间来测量所花费的时间

import time
time1=time.time()
#code
time2=time.time()
time=time2-time1
print(f"time taken timne seconds")