백준 2263번 : 트리의 순회 - Java

https://www.acmicpc.net/problem/2263

2263번: 트리의 순회

import java.util.Scanner;

class Tree {
    class Node{
        int data;
        Node left, right;
        Node(int data){
            this.data = data;
        }
    }
    Node root;
    static int pIndex = 0;

    public void buildTreeByInPost(int in[], int post[]){
        pIndex = post.length - 1;
        root = buildTreeByInPost(in ,post, 0, in.length-1);
    }

    private Node buildTreeByInPost(int in[], int post[], int start, int end){
        if(start > end) return null;
        Node node = new Node(post[pIndex--]);
        if(start==end) return node;
        int mid = search(in, start, end, node.data);

        node.right = buildTreeByInPost(in, post, mid+1, end);
        node.left = buildTreeByInPost(in, post, start, mid-1);
        return node;
    }

    private int search(int arr[], int start, int end, int value){
        int i;
        for(i=start; i<=end; i++){
            if(arr[i]==value) return i;
        }
        return i;
    }

    void printPreorder(Node node){
        if(node == null) return;
        System.out.print(node.data + " ");
        printPreorder(node.left);
        printPreorder(node.right);
    }
}

public class Main {
    public static void main(String args[]){
        int n;
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        int[] in = new int[n];
        int[] post = new int[n];

        for(int i=0; i<n;i++){
            in[i] = sc.nextInt();
        }

        for(int i=0; i<n;i++){
            post[i] = sc.nextInt();
        }

        Tree tree = new Tree();
        tree.buildTreeByInPost(in, post);
        tree.printPreorder(tree.root);
    }
}