programming-examples/java/Graph_Problems_Algorithms/Java Program to Implement Iterative Deepening.java

/*This Java program,Implements Iterative Deepening.Iterative deepening depth-first search(IDDFS) is a state space search strategy in which a depth-limited search is run repeatedly, increasing the depth limit with each iteration until it reaches , the depth of the shallowest goal state. IDDFS is equivalent to breadth-first search, but uses much less memory; on each iteration, it visits the nodes in the search tree in the same order as depth-first search, but the cumulative order in which nodes are first visited is effectively breadth-first.*/

import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.Stack;

public class IterativeDeepening
{
    private Stack<Integer> stack;
    private int numberOfNodes;
    private int depth;
    private int maxDepth;
    private boolean goalFound = false;

    public IterativeDeepening()
    {
        stack = new Stack<Integer>();
    }

    public void iterativeDeeping(int adjacencyMatrix[][], int destination)
    {
        numberOfNodes = adjacencyMatrix[1].length - 1;
        while (!goalFound)
            {
                depthLimitedSearch(adjacencyMatrix, 1, destination);
                maxDepth++;
            }
        System.out.println("\nGoal Found at depth " + depth);
    }

    private void depthLimitedSearch(int adjacencyMatrix[][], int source, int goal)
    {
        int element, destination = 1;
        int[] visited = new int[numberOfNodes + 1];
        stack.push(source);
        depth = 0;
        System.out.println("\nAt Depth " + maxDepth);
        System.out.print(source + "\t");
        while (!stack.isEmpty())
            {
                element = stack.peek();
                while (destination <= numberOfNodes)
                    {
                        if (depth < maxDepth)
                            {
                                if (adjacencyMatrix[element][destination] == 1)
                                    {
                                        stack.push(destination);
                                        visited[destination] = 1;
                                        System.out.print(destination + "\t");
                                        depth++;
                                        if (goal == destination)
                                            {
                                                goalFound = true;
                                                return;
                                            }
                                        element = destination;
                                        destination = 1;
                                        continue;
                                    }
                            }
                        else
                            {
                                break;
                            }
                        destination++;
                    }
                destination = stack.pop() + 1;
                depth--;
            }
    }

    public static void main(String... arg)
    {
        int number_of_nodes, destination;
        Scanner scanner = null;
        try
            {
                System.out.println("Enter the number of nodes in the graph");
                scanner = new Scanner(System.in);
                number_of_nodes = scanner.nextInt();
                int adjacency_matrix[][] = new int[number_of_nodes + 1][number_of_nodes + 1];
                System.out.println("Enter the adjacency matrix");
                for (int i = 1; i <= number_of_nodes; i++)
                    for (int j = 1; j <= number_of_nodes; j++)
                        adjacency_matrix[i][j] = scanner.nextInt();
                System.out.println("Enter the destination for the graph");
                destination = scanner.nextInt();
                IterativeDeepening iterativeDeepening = new IterativeDeepening();
                iterativeDeepening.iterativeDeeping(adjacency_matrix, destination);
            }
        catch (InputMismatchException inputMismatch)
            {
                System.out.println("Wrong Input format");
            }
        scanner.close();
    }
}

/*

Enter the number of nodes in the graph
7
Enter the adjacency matrix
0 1 1 0 0 0 0
0 0 0 1 1 0 0
0 0 0 0 0 1 1
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
Enter the destination for the graph
7

At Depth 0
1
At Depth 1
1	2	3
At Depth 2
1	2	4	5	3	6	7
Goal Found at depth 2