9.16 有效的括号 简单

 1 import java.util.Stack;
 2 class Solution {
 3     public boolean isValid(String s) {
 4         char[] brackets = s.toCharArray();
 5         Stack<Character> save = new Stack<Character>();
 6         int flag = 1;
 7         for(int i = 0; i < brackets.length; i++){
 8             switch(brackets[i]){
 9                 case ‘(‘:
10                 case ‘{‘:
11                 case ‘[‘:
12                     save.push(brackets[i]);
13                     break;
14                 case ‘)‘:
15                     if(!save.empty() && save.peek() == ‘(‘)
16                         save.pop();
17                     else flag = 0;
18                     break;
19                 case ‘}‘:
20                     if(!save.empty() && save.peek() == ‘{‘)
21                         save.pop();
22                     else flag = 0;
23                     break;
24                 case ‘]‘:
25                     if(!save.empty() && save.peek() == ‘[‘)
26                         save.pop();
27                     else flag = 0;
28                     break;
29             }
30         }
31         if(save.empty() && flag == 1) return true;
32         else return false;
33     }
34 }