Recursive, Tree, Graph(DFS, BFS 기초) - 이진트리순회(DFS : Depth-First Search)

class Node {
    int data;
    Node lt, rt;

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

public class Main {
    Node root;

    public static void DFS(Node root) {
        if (root == null) return;
        else {
            System.out.print(root.data + " ");
            DFS(root.lt);
            DFS(root.rt);
        }
    }

    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);
        DFS(tree.root);
    }
}

 

 

public static void DFS(Node root) {
    if (root == null) return;
    else {
        System.out.print(root.data + " ");
        DFS(root.lt);
        DFS(root.rt);
    }
}

- 전위순회 1 2 4 5 3 6 7 출력

 

public static void DFS(Node root) {
    if (root == null) return;
    else {
        DFS(root.lt);
        System.out.print(root.data + " ");
        DFS(root.rt);
    }
}

- 중위순회 4 2 5 1 6 3 7 출력

 

 

public static void DFS(Node root) {
    if (root == null) return;
    else {
        DFS(root.lt);
        DFS(root.rt);
        System.out.print(root.data + " ");
    }
}

- 후위순회 4 5 2 6 7 3 1 출력