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Commit e56ed5e

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1 parent 8c7d184 commit e56ed5e

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2 files changed

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2 files changed

+253
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Lines changed: 113 additions & 0 deletions
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import java.util.*;
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class NodeData {
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int value;
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int dist;
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NodeData(int value,int dist){
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this.value = value;
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this.dist = dist;
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}
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}
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public class Dijkstra_Ninjas {
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class Graph{
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ArrayList<ArrayList<NodeData>> g;
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int V;
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Graph(int V){
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this.V = V;
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this.g = new ArrayList<>();
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for(int i=0; i<V; i++)
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g.add(new ArrayList<>());
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}
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public void addEdge(int a, int b, int dist) {
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g.get(a).add(new NodeData(b,dist));
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g.get(b).add(new NodeData(a,dist));
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}
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public void dijkstra(int src) {
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int[] visited = new int[this.V];
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int[] dist = new int[this.V];
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for(int i=0; i<this.V; i++)
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dist[i] = Integer.MAX_VALUE;
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dist[src] = 0;
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dijkstra_util(src,dist,visited);
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display(dist);
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}
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public void dijkstra_util(int src, int[] dist,int[] visited) {
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if(src==-1)
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return;
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visited[src] = 1;
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for(NodeData c : this.g.get(src)) {
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if(dist[src]+c.dist<dist[c.value])
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dist[c.value] = dist[src]+c.dist;
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}
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int mindist = Integer.MAX_VALUE;
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int index = -1;
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for(int i=0; i<this.V; i++) {
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if(visited[i]==0 && dist[i]<mindist) {
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mindist = dist[i];
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index = i;
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}
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}
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dijkstra_util(index, dist, visited);
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}
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public void display(int[] arr) {
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for(int c:arr) {
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System.out.print(c+", ");
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}
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System.out.println();
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}
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}
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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Graph g = new Dijkstra_Ninjas().new Graph(5);
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g.addEdge(0, 1, 4);
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g.addEdge(1, 3, 5);
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g.addEdge(0, 2, 8);
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g.addEdge(1, 2, 2);
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g.addEdge(2, 3, 5);
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g.addEdge(2, 4, 9);
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g.addEdge(3, 4, 4);
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g.dijkstra(0);
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g = new Dijkstra_Ninjas().new Graph(9);
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g.addEdge(0, 1, 4);
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g.addEdge(2, 1, 8);
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g.addEdge(2, 3, 7);
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g.addEdge(3, 4, 9);
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g.addEdge(4, 5, 10);
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g.addEdge(6, 5, 2);
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g.addEdge(6, 7, 1);
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g.addEdge(0, 7, 8);
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g.addEdge(7, 8, 7);
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g.addEdge(6, 8, 6);
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g.addEdge(2, 8, 2);
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g.addEdge(2, 5, 4);
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g.addEdge(3, 5, 14);
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g.addEdge(7, 1, 11);
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g.dijkstra(0);
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}
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}
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import java.util.*;
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class Node implements Comparator<Node>{
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int data;
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int cost;
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public Node() {}
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public Node(int data, int cost) {
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this.data = data;
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this.cost = cost;
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}
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@Override
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public int compare(Node node1, Node node2) {
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// TODO Auto-generated method stub
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if (node1.cost < node2.cost)
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return -1;
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if (node1.cost > node2.cost)
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return 1;
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return 0;
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}
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@Override
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public String toString() {
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// TODO Auto-generated method stub
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return "("+this.data+","+this.cost+")";
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}
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}
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public class Dijkstra_PQ {
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class Graph{
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ArrayList<ArrayList<Node>> g;
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int V;
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Graph(int V){
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this.V = V;
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g = new ArrayList<>();
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for(int i=0; i<this.V; i++)
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g.add(new ArrayList<>());
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}
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public void addEdge(int a, int b,int dist) {
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this.g.get(a).add(new Node(b,dist));
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this.g.get(b).add(new Node(a,dist));
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}
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public void dijkstra(int src) {
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int[] dist = new int[this.V];
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for(int i=0; i<this.V; i++)
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dist[i] = Integer.MAX_VALUE;
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dist[src] = 0;
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PriorityQueue<Node> pq = new PriorityQueue<>(new Node());
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pq.add(new Node(src,0));
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HashSet<Integer> visited = new HashSet<>();
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while(visited.size()!=this.V) {
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int curr = pq.remove().data;
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visited.add(curr);
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visitNeighbors(curr,visited,dist,pq);
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}
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for(int d : dist) {
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System.out.print(d+", ");
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}
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System.out.println();
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System.out.println(pq);
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}
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public void visitNeighbors(int curr,HashSet<Integer> visited,int[] dist,PriorityQueue<Node> pq) {
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for(Node c : this.g.get(curr)) {
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if(!visited.contains(c.data)) {
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if(dist[curr]+c.cost<dist[c.data]) {
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dist[c.data] = dist[curr]+c.cost;
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pq.add(new Node(c.data,dist[c.data]));
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}
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}
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}
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}
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}
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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Graph g = new Dijkstra_PQ().new Graph(5);
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g.addEdge(0, 1, 4);
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g.addEdge(1, 3, 5);
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g.addEdge(0, 2, 8);
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g.addEdge(1, 2, 2);
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g.addEdge(2, 3, 5);
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g.addEdge(2, 4, 9);
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g.addEdge(3, 4, 4);
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g.dijkstra(0);
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g = new Dijkstra_PQ().new Graph(9);
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g.addEdge(0, 1, 4);
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g.addEdge(2, 1, 8);
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g.addEdge(2, 3, 7);
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g.addEdge(3, 4, 9);
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g.addEdge(4, 5, 10);
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g.addEdge(6, 5, 2);
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g.addEdge(6, 7, 1);
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g.addEdge(0, 7, 8);
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g.addEdge(7, 8, 7);
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g.addEdge(6, 8, 6);
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g.addEdge(2, 8, 2);
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g.addEdge(2, 5, 4);
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g.addEdge(3, 5, 14);
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g.addEdge(7, 1, 11);
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g.dijkstra(0);
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}
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}

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