题解 | #有效括号序列#

import java.util.*;


public class Solution {
    /**
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    public boolean isValid (String s) {
        Stack<Character> stack = new Stack<>();
        char[] arr = s.toCharArray();
        // stack.push(arr[0]);
        for(int i = 0; i < arr.length; i++){
            if(stack.isEmpty()){
                stack.push(arr[i]);
                continue;
            }
            Character c = arr[i];
            switch (c){
                case ')':
                    if(stack.peek() == '(') stack.pop();
                    break;
                case '}':
                    if(stack.peek() == '{') stack.pop();
                    break;
                case ']':
                    if(stack.peek() == '[') stack.pop();
                    break;
                default:
                    stack.push(c);
            }
        }
        return stack.isEmpty();
    }
}