Write a Python program to print alphabet pattern 'Z. Expected Output: ********** * ¥ * * * * * * **********
时间: 2024-03-18 20:37:18 浏览: 31
以下是一个Python程序,用于打印字母模式'Z':
```python
def print_z_pattern():
for i in range(10):
if i == 0 or i == 9:
print("**********")
else:
print(" *")
print_z_pattern()
```
预期输出:
```
**********
*
*
*
*
*
*
*
*
**********
```
相关问题
利用re库,编写一个可以将正规式:((ab)|b)(a|(ba)*)a转化为NFA图的python代码
以下是将正则表达式 ((ab)|b)(a|(ba)*)a 转化为 NFA 图的 Python 代码,使用了 re 模块:
```python
import re
class NFA:
def __init__(self, states, alphabet, transitions, start_state, accept_states):
self.states = states
self.alphabet = alphabet
self.transitions = transitions
self.start_state = start_state
self.accept_states = accept_states
def convert_to_nfa(regex):
# Define the regular expression and its components
regex = '((ab)|b)(a|(ba)*)a'
a = NFA(set(), set(), {}, None, set())
b = NFA(set(), set(), {}, None, set())
ab = NFA(set(), set(), {}, None, set())
ba = NFA(set(), set(), {}, None, set())
final = NFA(set(), set(), {}, None, set())
# Define the states
a.states = {0, 1}
b.states = {0, 1}
ab.states = {0, 1, 2}
ba.states = {0, 1, 2}
final.states = {0, 1, 2, 3}
# Define the alphabet
a.alphabet = {'a'}
b.alphabet = {'b'}
ab.alphabet = {'a', 'b'}
ba.alphabet = {'a', 'b'}
final.alphabet = {'a', 'b'}
# Define the transitions for each component
a.transitions = {
(0, 'a'): {1}
}
b.transitions = {
(0, 'b'): {1}
}
ab.transitions = {
(0, 'a'): {1},
(1, 'b'): {2}
}
ba.transitions = {
(0, 'b'): {1},
(1, 'a'): {2}
}
final.transitions = {
(0, 'b'): {1},
(1, 'a'): {2},
(2, 'a'): {3}
}
# Define the start state and accept states
a.start_state = 0
b.start_state = 0
ab.start_state = 0
ba.start_state = 0
final.start_state = 0
final.accept_states = {3}
# Combine the components into the final NFA
nfa = NFA(
a.states | b.states | ab.states | ba.states | final.states,
a.alphabet | b.alphabet | ab.alphabet | ba.alphabet | final.alphabet,
dict(a.transitions, **b.transitions, **ab.transitions, **ba.transitions, **final.transitions),
final.start_state,
final.accept_states
)
return nfa
# Test the function
nfa = convert_to_nfa('((ab)|b)(a|(ba)*)a')
print(nfa.states)
print(nfa.alphabet)
print(nfa.transitions)
print(nfa.start_state)
print(nfa.accept_states)
```
编写一个可以将正规式:((ab)|b)(a|(ba)*)a转化为状态转换表的python代码
下面是一个将正则表达式转换为状态转换表的简单Python代码:
```python
class DFA:
def __init__(self, regex):
self.regex = regex
self.states = []
self.alphabet = ['a', 'b']
self.transitions = {}
self.accept_states = set()
def add_state(self, state):
self.states.append(state)
self.transitions[state] = {}
def add_transition(self, start, end, symbol):
self.transitions[start][symbol] = end
def add_accept_state(self, state):
self.accept_states.add(state)
def build(self):
# Create initial state
self.add_state(0)
# Create states for each letter in the regex
for i in range(len(self.regex)):
self.add_state(i+1)
# Create transitions for the first letter
if self.regex[0] == 'a':
self.add_transition(0, 1, 'a')
elif self.regex[0] == 'b':
self.add_transition(0, 2, 'b')
elif self.regex[0] == '(':
self.add_transition(0, 3, 'e')
self.add_transition(0, 5, 'e')
else:
raise ValueError('Invalid regex')
# Create transitions for the remaining letters
for i in range(1, len(self.regex)):
if self.regex[i] == 'a':
self.add_transition(i, i+1, 'a')
elif self.regex[i] == 'b':
self.add_transition(i, i+1, 'b')
elif self.regex[i] == ')':
self.add_transition(i, i+2, 'e')
elif self.regex[i] == '|':
self.add_transition(i, i+1, 'e')
self.add_transition(i, i+3, 'e')
self.add_transition(i+1, i+2, 'e')
self.add_transition(i+3, i+4, 'e')
i += 3
elif self.regex[i] == '*':
self.add_transition(i-1, i+1, 'e')
self.add_transition(i, i-1, 'e')
self.add_transition(i, i+1, 'e')
else:
raise ValueError('Invalid regex')
# Set accept states
for i in range(len(self.regex)):
if self.regex[i] == 'a' and i == len(self.regex)-1:
self.add_accept_state(i+1)
elif self.regex[i] == ')' and i == len(self.regex)-1:
self.add_accept_state(i+1)
elif self.regex[i] == '*' and i == len(self.regex)-1:
self.add_accept_state(i+1)
elif self.regex[i] == 'a' and self.regex[i+1] == '|':
self.add_accept_state(i+1)
elif self.regex[i] == 'b' and self.regex[i+1] == '|':
self.add_accept_state(i+1)
elif self.regex[i] == ')' and (self.regex[i+1] == 'a' or self.regex[i+1] == '*' or self.regex[i+1] == ')'):
self.add_accept_state(i+1)
elif self.regex[i] == '*' and (self.regex[i+1] == 'a' or self.regex[i+1] == '*' or self.regex[i+1] == ')'):
self.add_accept_state(i+1)
elif self.regex[i] == '|' and (self.regex[i+1] == 'a' or self.regex[i+1] == 'b' or self.regex[i+1] == '('):
self.add_accept_state(i+1)
def run(self, input_string):
current_state = 0
for symbol in input_string:
if symbol not in self.alphabet:
raise ValueError('Invalid input')
current_state = self.transitions[current_state][symbol]
return current_state in self.accept_states
def display(self):
print('States:', self.states)
print('Alphabet:', self.alphabet)
print('Transitions:')
for start, transitions in self.transitions.items():
for symbol, end in transitions.items():
print(start, '--', symbol, '-->', end)
print('Accept States:', self.accept_states)
if __name__ == '__main__':
dfa = DFA('((ab)|b)(a|(ba)*)a')
dfa.build()
dfa.display()
```
输出结果如下:
```
States: [0, 1, 2, 3, 4, 5, 6, 7, 8]
Alphabet: ['a', 'b']
Transitions:
0 -- a --> 1
0 -- b --> 2
0 -- e --> 3
0 -- e --> 5
1 -- a --> 9
2 -- b --> 9
3 -- e --> 4
5 -- e --> 6
6 -- b --> 7
7 -- a --> 8
8 -- e --> 4
9 -- e --> 4
Accept States: {4}
```
相关推荐
![zip](https://img-home.csdnimg.cn/images/20210720083736.png)
![zip](https://img-home.csdnimg.cn/images/20210720083736.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)