GPT答：

7i24.cn

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    static int n;
    static char[] chs;
    static int[] w, p, l, r;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        chs = new char[n];
        w = new int[n];
        p = new int[2 * n - 1];
        l = new int[2 * n - 1];
        r = new int[2 * n - 1];

        for (int i = 0; i < n; i++) {
            chs[i] = sc.next().charAt(0);
            w[i] = sc.nextInt();
            p[i] = -1;
            l[i] = -1;
            r[i] = -1;
        }

        for (int i=n;i<2*n-1;i++) {
            // 找到权值最小的两个结点
            int minIndexOne=-1,minIndexTwo=-1,minValueOne=Integer.MAX_VALUE,minValueTwo=Integer.MAX_VALUE;

            for(int j=0;j<i;j++){
                if(p[j]==-1){
                    if(w[j]<minValueOne){
                        minIndexTwo=minIndexOne; minValueTwo=minValueOne;
                        minIndexOne=j; minValueOne=w[j];
                    }else if(w[j]<minValueTwo){
                        minIndexTwo=j; minValueTwo=w[j];
                    }
                }
             }

             // 合并这两个结点，构造新的父节点
             w[i]=minValueOne+minValueTwo;p[minIndexOne]=i;p[minIndexTwo]=i;l[i]=minIndexOne;r[i]=minIndexTwo;

         }

         // 输出哈夫曼树
         for(int i=0;i<n;i++){
             System.out.print(w[i]+" ");
             print(l,r,i);
             System.out.println(p[p.length-2]);
         }
     }

     private static void print(int[] l,int[] r,int index){
         if(l[index]!=-1 && r[index]!=-1){ 
              System.out.print((l[index]+r[index])+" ");
              print(l,r,l[index]);
              print(l,r,r[index]);
          }else{
              System.out.print("0 "+index+" "+index+" ");
          }
      }
}