leetcode 52: valid parentheses

Valid ParenthesesJan
30 '12

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.

class Solution {
public:
bool isValid(string s) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
stack<char> myStack;
char c;

for( int i=0; i<s.size(); i++) {
if( s[i] == '(' || s[i] == '[' || s[i] == '{') {
myStack.push( s[i] );
} else if( myStack.empty() ) {
return false;
} else if( s[i] == ')') {
c = myStack.top();
if( c!= '(' ) return false;
else myStack.pop();
} else if( s[i] == ']') {
c = myStack.top();
if( c!= '[' ) return false;
else myStack.pop();
} else if( s[i] == '}') {
c = myStack.top();
if( c!= '{' ) return false;
else myStack.pop();
} else {
return false;
}
}

return myStack.empty();
}
};