LeetCode - Valid Parentheses (Java)

public static boolean isValid(String s) { char[] charArray = s.toCharArray();   HashMap<Character, Character> map = new HashMap<Character, Character>(); map.put('(', ')'); map.put('[', ']'); map.put('{', '}');   Stack<Character> stack = new Stack<Character>();   for (Character c : charArray) { if (map.keySet().contains(c)) { stack.push(c); } else if (map.values().contains(c)) { if (!stack.isEmpty() && map.get(stack.peek()) == c) { stack.pop(); } else { return false; } } } return stack.isEmpty(); }

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