LeetCode:20

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package com.imooc.test;

import java.util.Scanner;
import java.util.Stack;

/**
 * @author tangxuejun
 * @version 2018/9/29 5:42 PM
 * leeteCode：20括号匹配
 */
public class BracketTest {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String pattern = scanner.next();
        System.out.println(isValid(pattern));
    }

    private static boolean isValid(String s) {
        if (s == null) {
            return false;
        }
        Stack<String> stack = new Stack<>();
        String[] splitStr = s.split("");
        //是否是成对
        if (splitStr.length % 2 != 0) {
            return false;
        }
        for (String s1 : splitStr) {
            switch (s1) {
                //将各种左括号入栈
                case "(":
                case "{":
                case "[":
                    stack.push(s1);
                    break;
                //如果遇到一个右括号，则去栈顶匹配其对应的左括号，如果不相等，则返回false，否则继续执行，知道全部执行成功
                case ")":
                    if (stack.empty() || !stack.pop().equals("(")) {
                        return false;
                    }
                    break;
                case "}":
                    if (stack.empty() || !stack.pop().equals("{")) {
                        return false;
                    }
                    break;
                case "]":
                    if (stack.empty() || !stack.pop().equals("[")) {
                        return false;
                    }
                    break;
            }
        }
        return true;
    }

}