[알고리즘 문제]이진트리 순회(레벨 탐색) - BFS

▷ 문제

아래 그림과 같은 이진트리를 레벨탐색 연습하세요.

레벨 탐색 순회 출력 : 1 2 3 4 5 6 7

▷ 풀이

import java.util.LinkedList;
import java.util.Queue;

class Node{
  int data;
  Node lt, rt;

  public Node(int data){
    this.data = data;
    lt = rt = null;
  }
}

public class Main {
  Node root; 

  public void BFS(Node root){
    Queue<Node> queue = new LinkedList<>();
    queue.add(root);
    int L = 0;

    while(!queue.isEmpty()){
      int len = queue.size();
      System.out.print(L + " : ");
      for(int i=0; i<len; i++){
        Node cur = queue.poll();
        System.out.print(cur.data + " ");
        if(cur.lt != null) queue.add(cur.lt);
        if(cur.rt != null) queue.add(cur.rt);
      }
      L++;
      System.out.println();
    }
  }

  public static void main(String[] args){
    Main tree = new Main();
    tree.root = new Node(1);
    tree.root.lt = new Node(2);
    tree.root.rt = new Node(3);
    tree.root.lt.lt = new Node(4);
    tree.root.lt.rt = new Node(5);
    tree.root.rt.lt = new Node(6);
    tree.root.rt.rt = new Node(7);

    tree.BFS(tree.root);
  }
}