作者：_大盗坂崎由莉nyS | 来源：互联网 | 2023-10-11 14:58
检查Python中的平衡括号原文:https://www.
检查 Python 中的平衡括号
原文:https://www . geesforgeks . org/检查平衡-python 括号/
给定一个表达式字符串，编写一个 python 程序来查找给定字符串是否有平衡括号。
示例:
Input : {[]{()}}
Output : Balanced
Input : [{}{}(]
Output : Unbalanced
方法#1 : 使用堆栈
检查平衡括号的一种方法是使用堆栈。每次遇到开括号时，将它推入堆栈，遇到闭括号时，将其与堆栈顶部匹配并弹出。如果堆栈末尾为空，则返回“平衡”，否则返回“不平衡”。
# Python3 code to Check for
# balanced parentheses in an expression
open_list = ["[","{","("]
close_list = ["]","}",")"]
# Function to check parentheses
def check(myStr):
stack = []
for i in myStr:
if i in open_list:
stack.append(i)
elif i in close_list:
pos = close_list.index(i)
if ((len(stack) > 0) and
(open_list[pos] == stack[len(stack)-1])):
stack.pop()
else:
return "Unbalanced"
if len(stack) == 0:
return "Balanced"
else:
return "Unbalanced"
# Driver code
string = "{[]{()}}"
print(string,"-", check(string))
string = "[{}{})(]"
print(string,"-", check(string))
string = "((()"
print(string,"-",check(string))
Output:
{[]{()}} - Balanced
[{}{})(] - Unbalanced
((() - Unbalanced
接近#2 : 使用队列
首先将左括号映射到相应的右括号。使用“I”迭代给定的表达式，如果“I”是开括号，则在队列中追加，如果“I”是闭括号，则检查队列是空的还是“I”是队列的顶部元素，如果是，则返回“不平衡”，否则返回“平衡”。
# Python3 code to Check for
# balanced parentheses in an expression
def check(expression):
open_tup = tuple('({[')
close_tup = tuple(')}]')
map = dict(zip(open_tup, close_tup))
queue = []
for i in expression:
if i in open_tup:
queue.append(map[i])
elif i in close_tup:
if not queue or i != queue.pop():
return "Unbalanced"
if not queue:
return "Balanced"
else:
return "Unbalanced"
# Driver code
string = "{[]{()}}"
print(string, "-", check(string))
string = "((()"
print(string,"-",check(string))
Output:
{[]{()}} - Balanced
((() - Unbalanced
方法#3 : 基于淘汰的
在每次迭代中，最里面的括号被淘汰(替换为空字符串)。如果我们以一个空字符串结束，我们的初始字符串是平衡的；否则，不会。
# Python3 code to Check for
# balanced parentheses in an expression
def check(my_string):
brackets = ['()', '{}', '[]']
while any(x in my_string for x in brackets):
for br in brackets:
my_string = my_string.replace(br, '')
return not my_string
# Driver code
string = "{[]{()}}"
print(string, "-", "Balanced"
if check(string) else "Unbalanced")
Output:
京公网安备 11010802041100号