Top, Bottom, Left and Right Views for a Graph

GraphViews.java

package graphs;
import java.util.*;
class Graph{
	Node root = null;
	Graph(){
		
	}
	static class Node{
		int data;
		Node left, right;
		Node(int data){
			this.data = data;
			left = right = null;
		}
	}
}
class GraphViews extends Graph{
	GraphViews() {
		super();
		spanMap = new TreeMap<>();
	}

	int depth = -1;
	int span = 0;
	SortedMap<Integer,Integer> spanMap;
	void leftView(Node root,int depth) {
		if(root == null) return;
		if(depth > this.depth) {
			System.out.println(root.data);
			this.depth = depth;
		}
		leftView(root.left, depth+1);
		leftView(root.right, depth + 1);
		
		
	}
	void rightView(Node root, int depth) {
		if(root == null) return;
		if(depth > this.depth) {
			System.out.println(root.data);
			this.depth = depth;
		}
		rightView(root.right, depth + 1);
		rightView(root.left, depth + 1);
	}
	void topView(Node root, int span) {
		if(root == null) return;
		if(!spanMap.containsKey(span)) {
			spanMap.put(span,root.data);
		}
		topView(root.left,span-1);
		topView(root.right,span+1);
	}
	void bottomView(Node root, int span,int depth) {
		if(root == null) return;
		if(depth > this.depth) {
			spanMap.put(span, root.data);
		}
		bottomView(root.left,span-1,depth+1);
		bottomView(root.right, span+1,depth+1);
		
	}
	void reset() {
		span = 0;
		depth = -1;
		spanMap.clear(); 
	}
}

public class SideViews {

	public static void main(String[] args) {
		GraphViews g = new GraphViews();
		g.root = new Graph.Node(1);
		g.root.left = new Graph.Node(2);
		g.root.right = new Graph.Node(3);
		g.root.left.left = new Graph.Node(4);
		g.root.right.right = new Graph.Node(5);
		g.root.right.right.right = new Graph.Node(6);
		g.root.left.right = new Graph.Node(7);
		g.root.left.right.left = new Graph.Node(8);
		g.root.right.left = new Graph.Node(9);
		g.root.right.right.left = new Graph.Node(10);
		g.root.right.right.left.left = new Graph.Node(11);
//						1
//					  /   \
//					 2     3
//					/ \   /  \
//				   4   7 9    5
//				      /     /  \
//				     8     10    6
//				     	  /
//				     	 11
		
		
		System.out.println("Left View");
		g.leftView(g.root, 0);
		g.reset();
		System.out.println("Right View");
		g.rightView(g.root, 0);
		g.reset();
		System.out.println("Top View");
		g.topView(g.root, 0);
		for(int key: g.spanMap.keySet()) {
//			System.out.print("(" + key + "," + g.spanMap.get(key) + ") ");
			System.out.print(g.spanMap.get(key) + " ");
		}
		System.out.println();
		g.reset();
		System.out.println("Bottom View");
		g.bottomView(g.root, 0,0);
		for(int key: g.spanMap.keySet()) {
//			System.out.print("(" + key + "," + g.spanMap.get(key) + ") ");
			System.out.print(g.spanMap.get(key) + " ");
		}
    
    //OUTPUT:
    //Left View
    //1
    //2
    //4
    //8
    //11
    //Right View
    //1
    //3
    //5
    //6
    //11
    //Top View
    //4 2 1 3 5 6 
    //Bottom View
    //4 8 11 10 5 6 
	}
}