1. 什麽是排列

比如0、1、2的全部排列是(0, 1, 2) (0, 2, 1) (1, 0, 2) (1, 2, 0) (2, 0, 1) (2, 1, 0)。

2. Python 代碼

def confict(stored, new):
    if new in stored:
        return True
    return False


def arrange(n, stored=()):
    for i in range(n):
        if not confict(stored, i):
            if len(stored) == n - 1:
                
 
yield (i,)
            else:
                for result in arrange(n, stored + (i,)):
                    yield (i,) + result

3. n = 4 時，輸出結果：

if __name__ == "__main__":
    i = 1
    for k in arrange(4):
        print("{:2d}: ".format(i), end="")
        print(k)
        i += 1

"""
 
output:
 1: (0, 1, 2, 3)
 2: (0, 1, 3, 2)
 3: (0, 2, 1, 3)
 4: (0, 2, 3, 1)
 5: (0, 3, 1, 2)
 6: (0, 3, 2, 1)
 7: (1, 0, 2, 3)
 8: (1, 0, 3, 2)
 9: (1, 2, 0, 3)
10: (1, 2, 3, 0)
11: (1, 3, 0, 2)
12: (1, 3, 2, 0)
13: (2, 0, 1, 3)
14: (2, 0, 3, 1)
15: (2, 1, 0, 3)
16: (2, 1, 3, 0)
17: (2, 3, 0, 1)
18: (2, 3, 1, 0)
19: (3, 0, 1, 2)
20: (3, 0, 2, 1)
21: (3, 1, 0, 2)
22: (3, 1, 2, 0)
23: (3, 2, 0, 1)
24: (3, 2, 1, 0)
 
"""

輸出N個數字的所有排列