Question: There are four numbers: 1, 2, 3, and 4. How many three-digit numbers can be formed that are different from each other and have no repetitive numbers? What are each?
Program analysis: The numbers that can be filled in the hundred, ten, and single digits are 1, 2, 3, and 4. Make up all arrangements and then remove the arrangements that do not meet the conditions.
Program source code
Method 1:
#!/usr/bin/python
# -*- coding: UTF-8 -*-
for i in range(1,5):
for j in range(1,5):
for k in range(1,5):
if( i != k ) and (i != j) and (j != k):
print i,j,k
The above example output is as follows:
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
Method 2:
Remove duplicate elements with collections
#!/usr/bin/env python
#-*- coding:utf-8 -*-
import pprint
list_num = ["1","2","3","4"]
list_result = []
for i in list_num:
for j in list_num:
for k in list_num:
if len(set(i + j + k)) == 3:
list_result += [int(i + j + k)]
print("can form %d three-digit numbers that are different from each other and have no repeated numbers: "%len(list_result))
(list_result)
The output result is the same as above, but there is one thing that is output in the form of a set.
Summarize
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Title of this article: Python outputs three-digit numbers composed of 1, 2, 3, 4 that are different and have no repetitions.
Address of this article: /jiaoben/python/