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iterator fix

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This commit is contained in:
pazis 2019-12-05 14:05:20 +00:00
parent 24859d45ab
commit 514e6de373
2 changed files with 179 additions and 180 deletions
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44
algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/prim/Prim.java
View File

@ -10,23 +10,21 @@ public class Prim {
private List<Vertex> graph; private List<Vertex> graph;
public Prim(List<Vertex> graph) { public Prim(List<Vertex> graph){
this.graph = graph; this.graph = graph;
} }
public void run() { public void run(){
if (graph.size() > 0) { if (graph.size() > 0){
graph.get(0) graph.get(0).setVisited(true);
.setVisited(true);
} }
while (isDisconnected()) { while (isDisconnected()){
Edge nextMinimum = new Edge(Integer.MAX_VALUE); Edge nextMinimum = new Edge(Integer.MAX_VALUE);
Vertex nextVertex = graph.get(0); Vertex nextVertex = graph.get(0);
for (Vertex vertex : graph) { for (Vertex vertex : graph){
if (vertex.isVisited()) { if (vertex.isVisited()){
Pair<Vertex, Edge> candidate = vertex.nextMinimum(); Pair<Vertex, Edge> candidate = vertex.nextMinimum();
if (candidate.getValue() if (candidate.getValue().getWeight() < nextMinimum.getWeight()){
.getWeight() < nextMinimum.getWeight()) {
nextMinimum = candidate.getValue(); nextMinimum = candidate.getValue();
nextVertex = candidate.getKey(); nextVertex = candidate.getKey();
} }
@ -37,38 +35,36 @@ public class Prim {
} }
} }
private boolean isDisconnected() { private boolean isDisconnected(){
for (Vertex vertex : graph) { for (Vertex vertex : graph){
if (!vertex.isVisited()) { if (!vertex.isVisited()){
return true; return true;
} }
} }
return false; return false;
} }
public String originalGraphToString() { public String originalGraphToString(){
StringBuilder sb = new StringBuilder(); StringBuilder sb = new StringBuilder();
for (Vertex vertex : graph) { for (Vertex vertex : graph){
sb.append(vertex.originalToString()); sb.append(vertex.originalToString());
} }
return sb.toString(); return sb.toString();
} }
public void resetPrintHistory() { public void resetPrintHistory(){
for (Vertex vertex : graph) { for (Vertex vertex : graph){
Iterator it = vertex.getEdges() Iterator<Map.Entry<Vertex,Edge>> it = vertex.getEdges().entrySet().iterator();
.entrySet()
.iterator();
while (it.hasNext()) { while (it.hasNext()) {
Map.Entry pair = (Map.Entry) it.next(); Map.Entry<Vertex,Edge> pair = it.next();
((Edge) pair.getValue()).setPrinted(false); pair.getValue().setPrinted(false);
} }
} }
} }
public String minimumSpanningTreeToString() { public String minimumSpanningTreeToString(){
StringBuilder sb = new StringBuilder(); StringBuilder sb = new StringBuilder();
for (Vertex vertex : graph) { for (Vertex vertex : graph){
sb.append(vertex.includedToString()); sb.append(vertex.includedToString());
} }
return sb.toString(); return sb.toString();

59
algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/prim/Vertex.java
View File

@ -12,7 +12,7 @@ public class Vertex {
private Map<Vertex, Edge> edges = new HashMap<>(); private Map<Vertex, Edge> edges = new HashMap<>();
private boolean isVisited = false; private boolean isVisited = false;
public Vertex(String label) { public Vertex(String label){
this.label = label; this.label = label;
} }
@ -28,9 +28,15 @@ public class Vertex {
return edges; return edges;
} }
public void addEdge(Vertex vertex, Edge edge) { public void addEdge(Vertex vertex, Edge edge){
if (this.edges.containsKey(vertex)){
if (edge.getWeight() < this.edges.get(vertex).getWeight()){
this.edges.replace(vertex, edge);
}
} else {
this.edges.put(vertex, edge); this.edges.put(vertex, edge);
} }
}
public boolean isVisited() { public boolean isVisited() {
return isVisited; return isVisited;
@ -40,18 +46,17 @@ public class Vertex {
isVisited = visited; isVisited = visited;
} }
public Pair<Vertex, Edge> nextMinimum() { public Pair<Vertex, Edge> nextMinimum(){
Edge nextMinimum = new Edge(Integer.MAX_VALUE); Edge nextMinimum = new Edge(Integer.MAX_VALUE);
Vertex nextVertex = this; Vertex nextVertex = this;
Iterator it = edges.entrySet() Iterator<Map.Entry<Vertex,Edge>> it = edges.entrySet().iterator();
.iterator();
while (it.hasNext()) { while (it.hasNext()) {
Map.Entry pair = (Map.Entry) it.next(); Map.Entry<Vertex,Edge> pair = it.next();
if (!((Vertex) pair.getKey()).isVisited()) { if (!pair.getKey().isVisited()){
if (!((Edge) pair.getValue()).isIncluded()) { if (!pair.getValue().isIncluded()) {
if (((Edge) pair.getValue()).getWeight() < nextMinimum.getWeight()) { if (pair.getValue().getWeight() < nextMinimum.getWeight()) {
nextMinimum = (Edge) pair.getValue(); nextMinimum = pair.getValue();
nextVertex = (Vertex) pair.getKey(); nextVertex = pair.getKey();
} }
} }
} }
@ -59,41 +64,39 @@ public class Vertex {
return new Pair<>(nextVertex, nextMinimum); return new Pair<>(nextVertex, nextMinimum);
} }
public String originalToString() { public String originalToString(){
StringBuilder sb = new StringBuilder(); StringBuilder sb = new StringBuilder();
Iterator it = edges.entrySet() Iterator<Map.Entry<Vertex,Edge>> it = edges.entrySet().iterator();
.iterator();
while (it.hasNext()) { while (it.hasNext()) {
Map.Entry pair = (Map.Entry) it.next(); Map.Entry<Vertex,Edge> pair = it.next();
if (!((Edge) pair.getValue()).isPrinted()) { if (!pair.getValue().isPrinted()) {
sb.append(getLabel()); sb.append(getLabel());
sb.append(" --- "); sb.append(" --- ");
sb.append(((Edge) pair.getValue()).getWeight()); sb.append(pair.getValue().getWeight());
sb.append(" --- "); sb.append(" --- ");
sb.append(((Vertex) pair.getKey()).getLabel()); sb.append(pair.getKey().getLabel());
sb.append("\n"); sb.append("\n");
((Edge) pair.getValue()).setPrinted(true); pair.getValue().setPrinted(true);
} }
} }
return sb.toString(); return sb.toString();
} }
public String includedToString() { public String includedToString(){
StringBuilder sb = new StringBuilder(); StringBuilder sb = new StringBuilder();
if (isVisited()) { if (isVisited()) {
Iterator it = edges.entrySet() Iterator<Map.Entry<Vertex,Edge>> it = edges.entrySet().iterator();
.iterator();
while (it.hasNext()) { while (it.hasNext()) {
Map.Entry pair = (Map.Entry) it.next(); Map.Entry<Vertex,Edge> pair = it.next();
if (((Edge) pair.getValue()).isIncluded()) { if (pair.getValue().isIncluded()) {
if (!((Edge) pair.getValue()).isPrinted()) { if (!pair.getValue().isPrinted()) {
sb.append(getLabel()); sb.append(getLabel());
sb.append(" --- "); sb.append(" --- ");
sb.append(((Edge) pair.getValue()).getWeight()); sb.append(pair.getValue().getWeight());
sb.append(" --- "); sb.append(" --- ");
sb.append(((Vertex) pair.getKey()).getLabel()); sb.append(pair.getKey().getLabel());
sb.append("\n"); sb.append("\n");
((Edge) pair.getValue()).setPrinted(true); pair.getValue().setPrinted(true);
} }
} }
} }