【LeetCode】20 - 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.

Tags： Stack String

Solution:

class Solution {
public:
bool isValid(string s) {
stack<char> stk;
for(int i=0;i<s.size();i++){
char c=s[i];
if(c=='('||c=='['||c=='{'){
stk.push(c);
}else if(c==')'||c=='}'||c==']'){
if(stk.empty())return false;
else{
char c2=stk.top();
stk.pop();
if((c2=='('&&c!=')')||(c2=='{'&&c!='}')||(c2=='['&&c!=']'))return false;
}
}
}
return stk.empty();
}
};