1991

Main.java

import java.util.*;
public class Main {
    public static void preorder(int[][] a, int x) {
        if (x == -1) return;
        System.out.print((char)(x+'A'));
        preorder(a,a[x][0]);
        preorder(a,a[x][1]);
    }
    public static void inorder(int[][] a, int x) {
        if (x == -1) return;
        inorder(a,a[x][0]);
        System.out.print((char)(x+'A'));
        inorder(a,a[x][1]);
    }
    public static void postorder(int[][] a, int x) {
        if (x == -1) return;
        postorder(a,a[x][0]);
        postorder(a,a[x][1]);
        System.out.print((char)(x+'A'));
    }
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        sc.nextLine();
        int[][] a = new int[26][2];
        for (int i=0; i<n; i++) {
            String line = sc.nextLine();
            int x = line.charAt(0) - 'A';
            char y = line.charAt(2);
            char z = line.charAt(4);
            if (y == '.') {
                a[x][0] = -1;
            } else {
                a[x][0] = y-'A';
            }
            if (z == '.') {
                a[x][1] = -1;
            } else {
                a[x][1] = z-'A';
            }
        }
        preorder(a,0);
        System.out.println();
        inorder(a,0);
        System.out.println();
        postorder(a,0);
        System.out.println();
    }
}