栈和队列的应用

Posted 2020-08-14 被罚站的树

package com.dy.xidian;

import java.util.Stack;

public class BracketMatch {

    public BracketMatch() {
        // TODO Auto-generated constructor stub
    }
    static final char[] dict = {‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘, ‘]‘};
    public static void main(String[] args) {
        String str1 = "({[]})[]";
        String str2 = "{([]}]";
        if (match(str1))
            System.out.println("合法");
        else
            System.out.println("不合法");
        if (match(str2))
            System.out.println("合法");
        else
            System.out.println("不合法");
    }

    public static boolean match(String str) {
        Stack<Character> stack = new Stack<>();
        stack.push(str.charAt(0));
        for (int i = 1; i < str.length(); i++) {
            if (dict[location(stack.peek()) + 1] != stack.peek())
                stack.push(str.charAt(i));
            else
                stack.pop();
        }
        if (stack.size() != 0) {
            return false;
        } else
            return true;
    }

    public static int location(char _c) {
        int i;
        for (i = 0; i < dict.length; i++) {
            if (dict[i] == _c)
                break;
        }
        if (i < dict.length)
            return i;
        else
            return -1;
    }
}

 

栈在括号匹配中的应用

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假设表达式中允许包含两种括号:圆括号和方括号，其嵌套的顺序任意，即([]())或者[([][])]等均为正确的表达式，[(])或([())均为不正确的格式。现在给一个表达式，判断其是否正确。