[LEEDCode][020][简单] – 有效的括号（valid-parentheses）

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.

给定一个只包括 '('，')'，'{'，'}'，'['，']' 的字符串，判断字符串是否有效。

有效字符串需满足：

左括号必须用相同类型的右括号闭合。
左括号必须以正确的顺序闭合。

注意空字符串可被认为是有效字符串。

示例 1:

<strong>输入:</strong> "()"
<strong>输出:</strong> true

1 2	<strong>输入:</strong> "()" <strong>输出:</strong> true

示例 2:

<strong>输入:</strong> "()[]{}"
<strong>输出:</strong> true

1 2	<strong>输入:</strong> "()[]{}" <strong>输出:</strong> true

示例 3:

<strong>输入:</strong> "(]"
<strong>输出:</strong> false

1 2	<strong>输入:</strong> "(]" <strong>输出:</strong> false

示例 4:

<strong>输入:</strong> "([)]"
<strong>输出:</strong> false

1 2	<strong>输入:</strong> "([)]" <strong>输出:</strong> false

示例 5:

<strong>输入:</strong> "{[]}"
<strong>输出:</strong> true

1 2	<strong>输入:</strong> "{[]}" <strong>输出:</strong> true

解答

class Solution:
    def isValid(self, s):
        """
        :type s: str
        :rtype: bool
        """
        dict = {
            '(':')',
            '[':']',
            '{':'}'
        }
        start = ''
        if len(s)%2 !=0:
            return False
        try:
            for i in s:
                if i in dict:
                    start = start + i
                elif dict[start[-1]] == i:
                        start = start[:-1]
                else:
                    return False
            if start == '':
                return True
            return False
        except:
            return False

class Solution:

def isValid(self, s):

"""

:type s: str

:rtype: bool

"""

dict = {

'(':')',

'[':']',

'{':'}'

}

start = ''

if len(s)%2 !=0:

return False

try:

for i in s:

if i in dict:

start = start + i

elif dict[start[-1]] == i:

start = start[:-1]

else:

return False

if start == '':

return True

return False

except:

return False

自测用例

try:
    print('---test1---')
    str = '()'
    prefix = Solution().isValid(str)
    print('true - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test2---')
    str = "()[]{}"
    prefix = Solution().isValid(str)
    print('true - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test3---')
    str = "([)]"
    prefix = Solution().isValid(str)
    print('false - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test4---')
    str = "(]"
    prefix = Solution().isValid(str)
    print('false - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test5---')
    str = "(("
    prefix = Solution().isValid(str)
    print('false - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test6---')
    str = "]"
    prefix = Solution().isValid(str)
    print('false - {}'.format(prefix))
except Exception as e:
    print(e)

try:
    print('---test7---')
    str = "["
    prefix = Solution().isValid(str)
    print('false - {}'.format(prefix))
except Exception as e:
    print(e)

try:

print('---test1---')

str = '()'

prefix = Solution().isValid(str)

print('true - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test2---')

str = "()[]{}"

prefix = Solution().isValid(str)

print('true - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test3---')

str = "([)]"

prefix = Solution().isValid(str)

print('false - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test4---')

str = "(]"

prefix = Solution().isValid(str)

print('false - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test5---')

str = "(("

prefix = Solution().isValid(str)

print('false - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test6---')

str = "]"

prefix = Solution().isValid(str)

print('false - {}'.format(prefix))

except Exception as e:

print(e)

try:

print('---test7---')

str = "["

prefix = Solution().isValid(str)

print('false - {}'.format(prefix))

except Exception as e:

print(e)

结果

提交时间	状态	执行用时	语言
几秒前	通过	44 ms	python3

解答

自测用例

结果

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