java 栈类的用法
数据结构中的栈,在解决很多问题都有用处,比如括号匹配,迷宫求解,表达式求值等等
java中有封装好的类,可以直接调用:
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Stack:
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1-->public Stack()创建一个空堆栈
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2-->public boolean empty()测试堆栈是否为空;
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3-->public E pop()移除堆栈顶部的对象,并作为此函数的值返回该对象。?
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4-->public E push(E item)把项压入堆栈顶部
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5-->public E peek()查看堆栈顶部的对象,但不从堆栈中移除它。?
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6-->public boolean empty()测试堆栈是否为空
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结合一道题目:
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括号配对问题3[(])(])([[]()])
NoNoYes
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代码:
import java.util.Scanner;import java.util.Stack;public class Main {public static void main(String[] args) {Scanner scan = new Scanner(System.in);int N = scan.nextInt();String s;for (int i = 0; i < N; i++) {s = scan.next();if (isMatch(s)) {System.out.println("Yes");} else {System.out.println("No");}}}private static boolean isMatch(String s) {Stack<Character> sk = new Stack<Character>();for (int i = 0; i < s.length(); i++) {if (s.charAt(i) == '(') {sk.push('(');}if (s.charAt(i) == ')') {if (!sk.isEmpty() && sk.pop() == '(')continue;elsereturn false;}if (s.charAt(i) == '[') {sk.push('[');}if (s.charAt(i) == ']') {if (!sk.isEmpty() && sk.pop() == '[')continue;elsereturn false;}}if (sk.isEmpty())return true;elsereturn false;}}?
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