题解 | 单词倒排

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String str = scanner.nextLine().trim();
            if ("exit".equalsIgnoreCase(str)) {
                break;
            }
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < str.length(); i++) {
                char c = str.charAt(i);
                if (!(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z')) {
                    c = ' ';
                }
                sb.append(c);
            }
            String[] res = sb.toString().split(" ");
            Stack<String> stack = new Stack<>();
            for (String s : res) {
                stack.push(s);
            }
            while (!stack.isEmpty()) {
                System.out.print(stack.pop() + " ");
            }
        }
        scanner.close();
    }
}