题目

image.png

思路

  • 利用栈进行比较

    代码

    1.   public boolean isValid(String s) {
    2.       int n = s.length();
    3.       if (n % 2 == 1) {
    4.           return false;
    5.       }
    7.       Map<Character, Character> pairs = new HashMap<Character, Character>() {{
    8.           put(')', '(');
    9.           put(']', '[');
    10.           put('}', '{');
    11.       }};
    12.       Deque<Character> stack = new LinkedList<Character>();
    13.       for (int i = 0; i < n; i++) {
    14.           char ch = s.charAt(i);
    15.           if (pairs.containsKey(ch)) {
    16.               if (stack.isEmpty() || stack.peek() != pairs.get(ch)) {
    17.                   return false;
    18.               }
    19.               stack.pop();
    20.           } else {
    21.               stack.push(ch);
    22.           }
    23.       }
    24.       return stack.isEmpty();
    25.   }

    有效括号