題目:有四個數字:1、2、3、4,能組成多少個互不相同且無重複數字的三位數?各是多少?
for i in range(1,5):
for j in range(1,5):
for k in range(1,5):
if(i!=j)&(i!=k)&(k!=j):
print (i,j,k)
結果:
(1, 2, 3)
(1, 2, 4)
(1, 3, 2)
(1, 3, 4)
(1, 4, 2)
(1, 4, 3)
(2, 1, 3)
(2, 1, 4)
(2, 3, 1)
(2, 3, 4)
(2, 4, 1)
(2, 4, 3)
(3, 1, 2)
(3, 1, 4)
(3, 2, 1)
(3, 2, 4)
(3, 4, 1)
(3, 4, 2)
(4, 1, 2)
(4, 1, 3)
(4, 2, 1)
(4, 2, 3)
(4, 3, 1)
(4, 3, 2)
#!/usr/bin/env python
# _*_ coding:utf-8 _*_
username = input("請輸入用戶名:")
password = input("請輸入密碼:")
if username == 'seven' and password == '123':
print("登錄成功")
else:
print("登錄失敗")
# cat a.py
#!/usr/bin/env python
# _*_ coding:utf-8 _*_
error_num = 0
while True:
username = input("請輸入用戶名:")
password = input("請輸入密碼:")
if username == 'seven' and password == '123':
print("登錄成功")
break
else:
print("登錄失敗")
error_num += 1
if error_num == 3:
exit()
else:
continue
# python3 a.py
請輸入用戶名:1
請輸入密碼:1
登錄失敗
請輸入用戶名:1
請輸入密碼:1
登錄失敗
請輸入用戶名:1
請輸入密碼:1
登錄失敗
mads@mads-virtual-machine:~$ python3 a.py
請輸入用戶名:seven
請輸入密碼:123
登錄成功