LeetCode题解——Valid Parentheses

Given a string containing just the characters

'('

,

')'

,

'{'

,

'}'

,

'['

and

']'

,
determine if the input string is valid.

The brackets must close in the correct order,

"()"

and

"()[]{}"

are
all valid but

"(]"

and

"([)]"

are
not.

重在对栈的使用

class Solution {
public:
bool isValid(string s) {
if(s.size()%2!=0 ) return false;
stack<char> st;

for(int i=0;i<s.size();i++)
{
if(st.empty()) st.push(s[i]);
else
{
char p = st.top();
if((p=='(' && s[i]==')')|| (p=='['&&s[i]==']') || (p=='{' && s[i]=='}')) st.pop();
else st.push(s[i]);
}
}
return st.empty();
}
};