import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class Graph {
private Set<Integer> marked = new HashSet<>();
private Map<Integer, Set<Integer>> neighbors = new HashMap<>();
private Integer goal;
private boolean reached;
private int count = 0;
public Set<Integer> getPoints() {
return neighbors.keySet();
}
public int size() {
return getPoints().size();
}
public long edgeSize() {
return neighbors.values().stream().collect(Collectors.summingLong(Set::size))/2;
}
public void addEdge(int a, int b) {
neighbors.computeIfAbsent(a, k -> new HashSet<Integer>()).add(b);
neighbors.computeIfAbsent(b, k -> new HashSet<Integer>()).add(a);
}
public void dfsGoalSearch(Integer start, Integer goal) {
this.goal = goal;
dfs(start);
}
public void dfs(Integer v) {
marked.add(v);
if(v.equals(goal)) reached = true;
for(Integer w : neighbors.get(v)) {
if(!marked.contains(w)) {
if(reached) {
System.out.println(v +"--" + w + "[label=" + count + ", color=blue,penwidth=3.0];");
}else{
System.out.println(v +"--" + w + "[label=" + count + ", color=red,penwidth=3.0];");
}
count++;
dfs(w);
}
}
}
public static void main(String...args) {
Graph g = new Graph();
//change the number of points and edges here.
for(int i = 0; i < 7; i++) {
g.addEdge(i, i + 1);
g.addEdge(i, i + 2);
}
for(int i = 15; i < 17; i++) {
g.addEdge(i, i+1);
}
g.addEdge(19, 19);
System.out.println("strict graph {");
g.neighbors.keySet().stream().forEach(i ->
{
Stream.of(g.neighbors.get(i)).flatMap(j -> j.stream())
.forEach(k -> System.out.println(i + "--" + k + ";"));
});
//change the start point and goal point here
g.dfsGoalSearch(3, 6);
System.out.println("}");
System.out.println("number of points: " + g.size());
System.out.println("number of edges: " + g.edgeSize());
System.out.println("can we reach point 6 from 3? " + g.marked.contains(6));
System.out.println("can we reach point 16 from 3? " + g.marked.contains(16));
System.out.println("can we reach point 19 from 3? " + g.marked.contains(19));
}
}
