Deepest First Search or DFS for a Graph - Java Data Structure

Java examples for Data Structure:Graph

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Description

Deepest First Search or DFS for a Graph

Demo Code

package com.company.algs.graph.dfs;

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

@SuppressWarnings({ "Duplicates", "WeakerAccess" })
public class DFS {
    public Vertex search(Vertex startVertex, String searchVertexName) {
        LinkedList<Vertex> stack = new LinkedList<>();
        stack.add(startVertex);//w  w w .ja  va  2  s.  co  m

        int step = -1;
        while (!stack.isEmpty()) {
            step++;
            Vertex top = stack.pollFirst();
            if (top.name.equals(searchVertexName)) {
                top.mark = true;
                top.step = step;
                return top;
            } else {
                if (!top.mark) {
                    top.mark = true;
                    for (Vertex v : top.adjacentVertices) {
                        if (!v.mark) {
                            v.depth = top.depth + 1;
                            stack.addFirst(v);
                        }
                    }
                }
            }
        }

        return null;
    }

    public void recursiveSearch(Vertex startVertex) {
        startVertex.mark = true;
        System.out.println("In: " + startVertex);
        for (Vertex v : startVertex.adjacentVertices) {
            if (!v.mark) {
                recursiveSearch(v);
            }
        }
        System.out.println("Out: " + startVertex);
    }

    public static void main(String[] args) {
        Vertex vertexA = new Vertex("A");
        Vertex vertexB = new Vertex("B");
        Vertex vertexC = new Vertex("C");
        Vertex vertexD = new Vertex("D");
        Vertex vertexE = new Vertex("E");
        Vertex vertexF = new Vertex("F");
        Vertex vertexG = new Vertex("G");

        vertexA.adjacentVertices = Arrays.asList(vertexB, vertexC);
        vertexB.adjacentVertices = Arrays.asList(vertexA, vertexD);
        vertexC.adjacentVertices = Arrays.asList(vertexA, vertexE);
        vertexD.adjacentVertices = Arrays.asList(vertexB, vertexE);
        vertexE.adjacentVertices = Arrays.asList(vertexC, vertexF, vertexD);
        vertexF.adjacentVertices = Arrays.asList(vertexE, vertexG);
        vertexG.adjacentVertices = Collections.singletonList(vertexF);

        DFS dfs = new DFS();
        dfs.recursiveSearch(vertexA);
        //        Vertex vertex = dfs.search(vertexA, "B");
        //        System.out.println(vertex == null ? "Not found" : vertex);
    }

    private static class Vertex {
        private List<Vertex> adjacentVertices;
        private String name;
        private int depth;
        private int step;
        private boolean mark;

        Vertex(String name) {
            this.name = name;
        }

        @Override
        public String toString() {
            return "Vertex{" + "name='" + name + '\'' + ", depth=" + depth
                    + ", mark=" + mark + ", step=" + step + '}';
        }
    }
}

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