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) {
stack<char> stk;
int size = s.size();
for(int i=;i<size;i++){
if(s[i]=='('||s[i]=='['||s[i]=='{'){
stk.push(s[i]);
}else{
if(stk.empty()){
return false;
}
char topCh = stk.top();
if((s[i]==']' && topCh=='[' )||
(s[i]==')' && topCh=='(' )||
(s[i]=='}' && topCh=='{' )
){
stk.pop();
}else{
return false;
}
}
}
return stk.empty()? true:false;
}
};