https://leetcode-cn.com/problems/valid-parentheses/

栈

 public boolean isValid(String s) {
     Stack<Character> stack = new Stack<>();
     char[] str = s.toCharArray();
     for (char c : str) {
         if (c == '(' || c == '{' || c == '[') {
             stack.push(c == '(' ? ')' : (c == '{' ? '}' : ']'));
         } else {
             if (stack.isEmpty()) {
                 return false;
             }
             if (c != stack.pop()) {
                 return false;
             }
         }
     }
     return stack.isEmpty();
 }