某程序设计语言中的pair是如下方式定义：type:=int|pair<type,type>.

输入int个数和字符串

请添加"<"和“>"将字符串匹配

如果不能匹配，请输出："Error occured"

例如：

输入：

3

pair pair int int int

输出：

pair<pair<int,int>,int>

输入：

1

pair int

输出：

Error occured

输入：

5

pair pair int pair int pair int int int

输出：

pair<pair<int,pair<int,pair<int,int>>>,int>

import java.util.Scanner;import java.util.Stack;public class Main2 {public static void main(String[] args) {Scanner input = new Scanner(System.in);int p = 0;// pair的个数int num = Integer.parseInt(input.nextLine().toString().trim());String str = input.nextLine();String[] arr = str.split(" ");for (int i = 0; i < arr.length; i++)if (arr[i].equals("pair"))p++;if (p != num - 1 || p + num != arr.length)System.out.println("Error occured");elseSystem.out.println(match(arr));}public static String match(String[] arr) {String str = "";Stack<String> stack = new Stack<String>();for (int i = 0; i < arr.length; i++) {if (arr[i].equals("pair")) {stack.push("pair");str += "pair<";} else if (stack.peek().equals("pair")) {stack.push("int");str += "int,";} else {stack.push("int");str += "int";stack.pop();// pop "int"stack.pop();// pop "int"stack.pop();// pop "pair"str += ">";while (!stack.empty() && stack.peek().equals("int")) {str += ">";stack.pop();// pop "int"stack.pop();// pop "pair"}if (i != arr.length - 1) {str += ",";stack.push("int");}}}if (!stack.empty())return "Error occured";return str;}}