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younghohyounghoh
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add Dijkstra & Prim / modify README.md
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‎06/Dijkstra.java

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package hw06;
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public class Dijkstra {
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private final int MAX_VALUE = Integer.MAX_VALUE;
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private int[][] adjacencyMatrix ;
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private int dist[];
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public Dijkstra(){
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this.adjacencyMatrix = new int[][] {
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{ 0, 10, 3, MAX_VALUE, MAX_VALUE },
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{ MAX_VALUE, 0, 1, 2, MAX_VALUE },
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{ MAX_VALUE, 4, 0, 8, 2 },
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{ MAX_VALUE, MAX_VALUE, MAX_VALUE, 0, 7 },
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{ MAX_VALUE, MAX_VALUE, MAX_VALUE, 9, 0 }
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};
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}
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public void dijkstra(){
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this.dist = new int[5];
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for(int i = 0; i < 5; i++){
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this.dist[i] = MAX_VALUE;
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}
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this.dist[0] = 0;
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int count = 0;
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PriorityQueue q = new PriorityQueue();
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q.insert(new Node(0,0));
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for(int i = 0; i < dist.length - 1 ; i++){
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q.insert(new Node(i+1, MAX_VALUE));
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}
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while(q.getQueueSize() != 0){
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Node minNode = q.extractMin();
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int vertex = minNode.getVertex();
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System.out.println("===========================================================");
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System.out.println("S["+ count +"] : d[" + (char)(vertex + 65) +"] = "+ dist[vertex]);
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System.out.println("-----------------------------------------------------------");
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for(int i = 0; i < q.getQueueSize() ; i++){
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int adjVertex = q.getNode(i).getVertex();
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System.out.print("Q[" + i + "] : d[" + (char)(adjVertex + 65) + "] = " + dist[adjVertex]);
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if(this.adjacencyMatrix[vertex][adjVertex] != MAX_VALUE && dist[adjVertex] > dist[vertex] + this.adjacencyMatrix[vertex][adjVertex]){
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dist[adjVertex] = dist[vertex] + this.adjacencyMatrix[vertex][adjVertex];
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System.out.println(" => d[" + (char)(adjVertex + 65) + "] = " + dist[adjVertex]);
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q.update(adjVertex, dist[adjVertex]);
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continue;
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}
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System.out.println();
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}
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System.out.println();
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// System.out.println("===========================================================");
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count++;
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}
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}
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private class PriorityQueue{
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private Node[] heap;
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private int heapSize;
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public PriorityQueue(){
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}
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private void buildMinHeap(Node[] arr){
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for(int i = (this.heapSize) / 2 ; i > 0 ; i--){
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minHeapify(arr, i);
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}
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}
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private void minHeapify(Node[] arr, int i){
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int smallest;
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int leftChildIdx = getLeftChildIdx(i);
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int rightChildIdx = getRightChildIdx(i);
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if(this.heapSize >= leftChildIdx && arr[leftChildIdx].dist < arr[i].dist){
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smallest = leftChildIdx;
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}else{
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smallest = i;
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}
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if(this.heapSize >= rightChildIdx && arr[rightChildIdx].dist < arr[smallest].dist){
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smallest = rightChildIdx;
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}
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if(smallest != i){
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swap(arr, smallest, i);
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minHeapify(arr, smallest);
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}
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}
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public Node getNode(int index){
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return this.heap[index+1];
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}
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public int getQueueSize(){
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return this.heapSize;
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}
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public void update(int vertex, int newDist){
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for(int i = 1 ; i <= this.heapSize; i++){
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if(this.heap[i].vertex == vertex){
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this.heap[i].dist = newDist;
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break;
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}
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}
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buildMinHeap(this.heap);
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}
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public Node extractMin(){
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Node minNode = heap[1];
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swap(heap, heapSize, 1);
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this.heapSize--;
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buildMinHeap(heap);
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return minNode;
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}
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public void insert(Node x){
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Node[] temp = new Node[this.heapSize + 2];
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for(int i = 1 ; i <= this.heapSize; i++){
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temp[i] = heap[i];
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}
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temp[temp.length - 1] = x;
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this.heap = temp;
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this.heapSize = temp.length - 1;
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if(this.heapSize != 1 && this.heap[this.heapSize/2].dist < this.heap[this.heapSize].dist) return;
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buildMinHeap(this.heap);
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}
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private void swap(Node[] arr, int i, int j){
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Node temp = arr[i];
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arr[i] = arr[j];
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arr[j] = temp;
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}
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private int getLeftChildIdx(int parentIdx){
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return 2*parentIdx;
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}
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private int getRightChildIdx(int parentIdx){
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return 2*parentIdx+1;
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}
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}
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private class Node{
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private int dist;
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private int vertex;
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public Node(int vertex, int dist){
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this.vertex = vertex;
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this.dist = dist;
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}
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public int getDist() {
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return dist;
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}
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public int getVertex() {
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return vertex;
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}
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}
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}

‎06/Dijkstra2.java

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package hw06;
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public class Dijkstra2 {
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private final int MAX_VALUE = Integer.MAX_VALUE;
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private int[][] adjacencyMatrix ;
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private int dist[];
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private boolean visited[];
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public Dijkstra2(){
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this.adjacencyMatrix = new int[][] {
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{ 0, 10, 3, MAX_VALUE, MAX_VALUE },
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{ MAX_VALUE, 0, 1, 2, MAX_VALUE },
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{ MAX_VALUE, 4, 0, 8, 2 },
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{ MAX_VALUE, MAX_VALUE, MAX_VALUE, 0, 7 },
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{ MAX_VALUE, MAX_VALUE, MAX_VALUE, 9, 0 }
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};
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}
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public void dijkstra(){
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this.dist = new int[5];
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for(int i = 0; i < 5; i++){
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this.dist[i] = MAX_VALUE;
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}
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this.dist[0] = 0;
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this.visited = new boolean[5];
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int count = 0;
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PriorityQueue q = new PriorityQueue();
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q.insert(new Node(0,0));
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// for(int i = 0; i < dist.length - 1 ; i++){
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// q.insert(new Node(i+1, MAX_VALUE));
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// }
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while(q.getQueueSize() != 0){
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Node minNode = q.extractMin();
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int vertex = minNode.getVertex();
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if(visited[vertex]) continue; // 방문한 정점이면 인접 정점의 최소값 다시 찾지 않음
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visited[vertex] = true;
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System.out.println("===========================================================");
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System.out.println("S["+ count +"] : d[" + (char)(vertex + 65) +"] = "+ dist[vertex]);
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System.out.println("-----------------------------------------------------------");
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for(int i = 0; i < this.adjacencyMatrix[vertex].length ; i++){
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if(visited[i]) continue; // 인접노드 방문 했다면 다시 방문 X
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int adjVertex = i;
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System.out.print("Q[" + i + "] : d[" + (char)(adjVertex + 65) + "] = " + dist[adjVertex]);
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if(this.adjacencyMatrix[vertex][adjVertex] != MAX_VALUE && dist[adjVertex] > dist[vertex] + this.adjacencyMatrix[vertex][adjVertex]){
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dist[adjVertex] = dist[vertex] + this.adjacencyMatrix[vertex][adjVertex];
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System.out.println(" => d[" + (char)(adjVertex + 65) + "] = " + dist[adjVertex]);
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q.insert(new Node(adjVertex, dist[adjVertex]));
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// q.update(adjVertex, dist[adjVertex]);
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continue;
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}
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System.out.println();
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}
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System.out.println();
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// System.out.println("===========================================================");
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count++;
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}
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}
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private class PriorityQueue{
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private Node[] heap;
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private int heapSize;
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public PriorityQueue(){
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}
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private void buildMinHeap(Node[] arr){
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for(int i = (this.heapSize) / 2 ; i > 0 ; i--){
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minHeapify(arr, i);
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}
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}
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private void minHeapify(Node[] arr, int i){
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int smallest;
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int leftChildIdx = getLeftChildIdx(i);
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int rightChildIdx = getRightChildIdx(i);
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if(this.heapSize >= leftChildIdx && arr[leftChildIdx].dist < arr[i].dist){
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smallest = leftChildIdx;
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}else{
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smallest = i;
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}
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if(this.heapSize >= rightChildIdx && arr[rightChildIdx].dist < arr[smallest].dist){
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smallest = rightChildIdx;
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}
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if(smallest != i){
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swap(arr, smallest, i);
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minHeapify(arr, smallest);
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}
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}
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public Node getNode(int index){
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return this.heap[index+1];
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}
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public int getQueueSize(){
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return this.heapSize;
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}
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public void update(int vertex, int newDist){
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for(int i = 1 ; i <= this.heapSize; i++){
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if(this.heap[i].vertex == vertex){
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this.heap[i].dist = newDist;
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break;
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}
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}
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buildMinHeap(this.heap);
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}
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public Node extractMin(){
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Node minNode = heap[1];
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swap(heap, heapSize, 1);
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this.heapSize--;
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buildMinHeap(heap);
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return minNode;
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}
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public void insert(Node x){
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Node[] temp = new Node[this.heapSize + 2];
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for(int i = 1 ; i <= this.heapSize; i++){
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temp[i] = heap[i];
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}
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temp[temp.length - 1] = x;
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this.heap = temp;
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this.heapSize = temp.length - 1;
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if(this.heapSize != 1 && this.heap[this.heapSize/2].dist < this.heap[this.heapSize].dist) return;
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buildMinHeap(this.heap);
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}
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private void swap(Node[] arr, int i, int j){
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Node temp = arr[i];
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arr[i] = arr[j];
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arr[j] = temp;
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}
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private int getLeftChildIdx(int parentIdx){
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return 2*parentIdx;
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}
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private int getRightChildIdx(int parentIdx){
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return 2*parentIdx+1;
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}
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}
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private class Node{
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private int dist;
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private int vertex;
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public Node(int vertex, int dist){
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this.vertex = vertex;
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this.dist = dist;
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}
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public int getDist() {
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return dist;
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}
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public int getVertex() {
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return vertex;
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}
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}
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}

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