擅长:python、mysql、java
<pre><code>class py_solution:
def is_valid_parenthese(self, str1):
stack=[]
pchar = {"(": ")", "{": "}", "[": "]"}
for parenthese in str1:
if parenthese in pchar:
stack.append(parenthese)
elif len(stack) == 0 or pchar[stack.pop()] != parenthese:
return False
return len(stack) == 0
st=raw_input("Enter string of parenthesis")
print(py_solution().is_valid_parenthese(st))
</code></pre>
<p>如果输入是'{}',它会将'{'推到'If'条件下进行堆栈,然后副词是'{',它不在字典中爸爸。实际上值将为pop出去。那个poped值与当前参数'{'。Accordinglt false和true返回。你知道吗</p>