Ticket/#5 Add exercise to implement Dijkstra algorithm

dijkstra-algorithm/src/main/java/com/bobocode/GraphImpl.java

@@ -4,23 +4,70 @@
 
 import java.util.Set;
 
+/**
+ * {@link GraphImpl} implements Graph {@link Graph}, using nodes as vertices. Nodes are stores in instances of nested
+ * class Node. The graph can be initialized from a file, or by calling methods to add a node {@link GraphImpl#addNode(String)}
+ * and add an edge {@link GraphImpl#addDestination(String, String, int)}
+ *
+ */
 public class GraphImpl implements Graph {
 
+    /**
+     * This method creates a Graph from file
+     *
+     * File format e.g.
+     * nodeA nodeB nodeC
+     * nodeA nodeB 1
+     * nodeA nodeC 12
+     * @param fileName file contains graph struct
+     * @return a new graph contains vertices and edges
+     */
+    @Override
+    public Graph fromFile(String fileName) {
+        throw new UnsupportedOperationException("This method is not implemented yet"); // todo: implement this method
+    }
+
+    /**
+     * Adds a node to the graph, if it doesn't exist
+     *
+     * @param nodeName name of node to add
+     */
     @Override
     public void addNode(String nodeName) {
         throw new UnsupportedOperationException("This method is not implemented yet"); // todo: implement this method
     }
 
+    /**
+     * Adds a edge to the graph between nodes
+     *
+     * @param nodeFromName name of first node in edge
+     * @param nodeToName name of second node in edge
+     * @param distance the weight of edge
+     */
     @Override
     public void addDestination(String nodeFromName, String nodeToName, int distance) {
         throw new UnsupportedOperationException("This method is not implemented yet"); // todo: implement this method
     }
 
+    /**
+     * Calculates shortest distance between two nodes
+     *
+     * @param nodeStart name of node start path
+     * @param nodeEnd name of node finish path
+     * @return min distance between two nodes
+     */
     @Override
     public int calculateShortestDistance(String nodeStart, String nodeEnd) {
         throw new UnsupportedOperationException("This method is not implemented yet"); // todo: implement this method
     }
 
+    /**
+     * Calculates shortest path between two nodes
+     *
+     * @param nodeStart name of node start path
+     * @param nodeEnd name of node finish path
+     * @return set of nodes, contains min path between two nodes
+     */
     @Override
     public Set<String> calculateShortestPath(String nodeStart, String nodeEnd) {
         throw new UnsupportedOperationException("This method is not implemented yet"); // todo: implement this method

dijkstra-algorithm/src/main/java/com/bobocode/interfaces/Graph.java

@@ -1,10 +1,55 @@
 package com.bobocode.interfaces;
 
 import java.util.Set;
-
+/**
+ * Graph is a structure amounting to a set of objects in which some pairs of the objects are in some sense "related".
+ */
 public interface Graph {
+    /**
+     * Adds new vertices in graph.
+     *
+     * @param nodeName the name of node to add
+     */
     void addNode(String nodeName);
+
+    /**
+     * Adds edge between two vertices.
+     *
+     * @param nodeFromName the name of first node in edge
+     * @param nodeToName the name of second node in edge
+     * @param distance distance between vertices
+     */
     void addDestination(String nodeFromName, String nodeToName, int distance);
+
+    /**
+     * Returns shortest distance between two vertices
+     *
+     * @param nodeStart the name of start node
+     * @param nodeEnd the name of finish node
+     * @return an integer value that is distance between vertices
+     */
     int calculateShortestDistance(String nodeStart, String nodeEnd);
+
+    /**
+     * Returns shortest path between two vertices
+     *
+     * @param nodeStart the name of start node
+     * @param nodeEnd the name of finish node
+     * @return a set that contains node names for shortest path between vertices
+     */
     Set<String> calculateShortestPath(String nodeStart, String nodeEnd);
+
+    /**
+     * Returns configured Graph from file
+     *
+     * File format e.g.
+     * nodeA nodeB nodeC
+     *
+     * nodeA nodeB 1
+     * nodeA nodeC 12
+     *
+     * @param fileName the name of file, which contains graph
+     * @return a graph that contains vertices from file
+     */
+    Graph fromFile(String fileName);
 }

dijkstra-algorithm/src/test/java/com/bobocode/GraphImplTest.java

@@ -150,4 +150,12 @@ public void testIncorrectDistanceIntoGraph() {
             fail("Exception must be IncorrectDistanceException");
         }
     }
+
+    @Test
+    public void testCorrectCalculateGraphFromFile() {
+        graph = graph.fromFile("graph.txt");
+
+        assertEquals(graph.calculateShortestDistance("nodeA", "nodeG"), 19);
+        assertEquals(graph.calculateShortestPath("nodeA", "nodeC"), Set.of("nodeA", "nodeC", "nodeE", "nodeG"));
+    }
 }

linked-queue/src/test/resources/graph.txt

@@ -0,0 +1,12 @@
+nodeA nodeB nodeC nodeD nodeE nodeF nodeG
+nodeA nodeB 10
+nodeA nodeC 8
+nodeB nodeD 3
+nodeC nodeE 8
+nodeC nodeF 16
+nodeC nodeG 25
+nodeD nodeE 5
+nodeD nodeF 3
+nodeE nodeF 2
+nodeE nodeG 3
+nodeF nodeG 6