Leetcode (Valid) parentheses

Topic

Given A string containing just the characters ' (', ') ', ' {', '} ', ' [' and '] ', determine if the input string is valid.

The brackets must close in the correct order, "()" and "() []{}" is all valid but "(]" and "([)]" is not.

Analysis

Typical examples of parentheses matching problems, data structures in a book. Its program implementation, the use of stack structure is the best method.

AC Code

classSolution { Public:BOOLIsValid (strings) {intLen =strlen(S.c_str ());if(len = =0)return true;if(Len%2!=0)return false;//bracket matching problem, with data structure stack auxiliary implementation         Stack<char>Sta for(inti =0; i < Len; i++) {if(S[i]! =' ) '&& S[i]! ='] '&& S[i]! ='} ') Sta.push (S[i]);Else{if(Sta.size () <=0)return false;if(S[i] = = Pairletter (Sta.top ())) Sta.pop ();Else                    return false; }//else}//for        if(sta.size () = =0)return true;Else            return false; }CharPairletter (Const Char&AMP;C) {Switch(c) { Case ' (':return ' ) '; Break; Case ' [':return '] '; Break; Case ' {':return '} '; Break;default:return 0; Break; }    }};

GitHub test Program source code

Leetcode (Valid) parentheses