[leetcode]Valid Parentheses

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public class Solution { public boolean isValid(String s) { Stack<Character> lookup = new Stack<Character>(); for (int i = 0; i < s.length(); i++){ char temp = s.charAt(i); if (isFaceRight(temp)) lookup.push(temp); else{ if (lookup.isEmpty() || lookup.peek() != match(temp)) return false; lookup.pop(); } } return lookup.isEmpty(); } private boolean isFaceRight(char a){ return a == '(' || a == '{' || a == '['; } private char match(char a){ if (a == ')') return '('; if (a == '}') return '{'; return '['; } }