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.
1 class Solution { 2 public: 3 bool isValid(string s) { 4 stack<char> stk; 5 char c; 6 7 for(int i=0;i<s.size();i++) 8 { 9 if(s[i]=='('||s[i]=='['||s[i]=='{') 10 stk.push(s[i]); 11 else if(stk.empty()) 12 return false; 13 else if(s[i]==')') 14 { 15 c=stk.top(); 16 if(c=='(') 17 stk.pop(); 18 else 19 return false; 20 } 21 else if(s[i]==']') 22 { 23 c=stk.top(); 24 if(c=='[') 25 stk.pop(); 26 else 27 return false; 28 } 29 else if(s[i]=='}') 30 { 31 c=stk.top(); 32 if(c=='{') 33 stk.pop(); 34 else 35 return false; 36 } 37 } 38 39 if(stk.empty()==false) return false; 40 41 return true; 42 } 43 };
