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completed dfs-build #3

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completed dfs-build #3

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66 changes: 63 additions & 3 deletions src/Build.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,17 @@ public class Build {
* @param k the maximum word length (exclusive)
*/
public static void printShortWords(Vertex<String> vertex, int k) {
Set<Vertex<String>> reachable = new HashSet<>();
printShortWords(vertex, k, reachable);
}

public static <T> void printShortWords(Vertex<String> vertex, int k, Set<Vertex<String>> reachable) {
if(vertex == null || reachable.contains(vertex)) return;
reachable.add(vertex);
if(vertex.data.length() < k) System.out.println(vertex.data);
for(Vertex<String> neighbor : vertex.neighbors) {
printShortWords(neighbor, k, reachable);
}
}

/**
Expand All @@ -23,7 +34,20 @@ public static void printShortWords(Vertex<String> vertex, int k) {
* @return the longest reachable word, or an empty string if the vertex is null
*/
public static String longestWord(Vertex<String> vertex) {
return "";
Set<Vertex<String>> reachable = new HashSet<>();
String longest = "";
return longestWord(vertex, reachable, longest);
}

public static String longestWord(Vertex<String> vertex, Set<Vertex<String>> reachable, String longest) {
if(vertex == null || reachable.contains(vertex)) return longest;
reachable.add(vertex);
if(vertex.data.length() > longest.length()) longest = vertex.data;
for(Vertex<String> neighbor : vertex.neighbors) {
String temp = longestWord(neighbor, reachable, longest);
if(temp.length() > longest.length()) longest = temp;
}
return longest;
}

/**
Expand All @@ -34,6 +58,17 @@ public static String longestWord(Vertex<String> vertex) {
* @param <T> the type of values stored in the vertices
*/
public static <T> void printSelfLoopers(Vertex<T> vertex) {
Set<Vertex<T>> reachable = new HashSet<>();
printSelfLoopers(vertex, reachable);
}

public static <T> void printSelfLoopers(Vertex<T> vertex, Set<Vertex<T>> reachable ) {
if(vertex == null || reachable.contains(vertex)) return;
reachable.add(vertex);
if(vertex.neighbors.contains(vertex)) System.out.println(vertex.data);
for(Vertex<T> neighbor : vertex.neighbors) {
printSelfLoopers(neighbor, reachable);
}
}

/**
Expand All @@ -45,9 +80,20 @@ public static <T> void printSelfLoopers(Vertex<T> vertex) {
* @return true if the destination is reachable from the start, false otherwise
*/
public static boolean canReach(Airport start, Airport destination) {
return false;
Set<Airport> reachable = new HashSet<>();
return canReach(start, destination, reachable);
}

public static boolean canReach(Airport start, Airport destination, Set<Airport> reachable) {
if(start == null || reachable.contains(start)) return false;
if(start == destination ) return true;
reachable.add(start);
for(Airport airport : start.getOutboundFlights()) {
if(canReach(airport, destination, reachable)) return true;
}
return false;
}

/**
* Returns the set of all values in the graph that cannot be reached from the given starting value.
* The graph is represented as a map where each vertex is associated with a list of its neighboring values.
Expand All @@ -58,6 +104,20 @@ public static boolean canReach(Airport start, Airport destination) {
* @return a set of values that cannot be reached from the starting value
*/
public static <T> Set<T> unreachable(Map<T, List<T>> graph, T starting) {
return new HashSet<>();
if(!graph.keySet().contains(starting)) return graph.keySet();
Set<T> reachable = new HashSet<>();
Set<T> unreachable = new HashSet<>();
reachable(graph, starting, reachable);
for(T value : graph.keySet()) {
if(!reachable.contains(value)) unreachable.add(value);
}
return unreachable;
}
public static <T> void reachable(Map<T, List<T>> graph, T starting, Set<T> reachable) {
if(starting == null || reachable.contains(starting)) return;
reachable.add(starting);
for(T value : graph.get(starting)) {
reachable(graph, value, reachable);
}
}
}