腾讯2020校招后台 压缩算法

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        sc.close();
        
        while(str.contains("]")) {
            int right = str.indexOf("]");
            int left = str.lastIndexOf("[",right);
            
            String s = str.substring(left+1,right);
            String[] p = s.split("\\|");
            
            str = str.replace("[" + s + "]",String.join("",Collections.nCopies(Integer.parseInt(p[0]),p[1])));
        }
        
        System.out.println(str);
    }
}