mirror of
https://github.com/TheAlgorithms/Java.git
synced 2025-07-10 21:43:15 +08:00
Created Graph Algos
it contains Dijkstra, Prims, dft, bft, dfs, bfs and many more.
This commit is contained in:
Ritik2604
437
DataStructures/Graphs/GraphAlgos
Normal file
437
DataStructures/Graphs/GraphAlgos
Normal file
@ -0,0 +1,437 @@
|
||||
import java.util.ArrayList;
|
||||
import java.util.HashMap;
|
||||
import java.util.LinkedList;
|
||||
import Heaps.GenericHeap;
|
||||
public class Graph {
|
||||
private class vertex{
|
||||
HashMap<String,Integer> nbrs=new HashMap<>();
|
||||
}
|
||||
HashMap<String,vertex> vertcs;
|
||||
public Graph(){
|
||||
vertcs=new HashMap<>();
|
||||
}
|
||||
public int numVertex() {
|
||||
return this.vertcs.size();
|
||||
}
|
||||
public boolean containsVertex(String vname) {
|
||||
return this.vertcs.containsKey(vname);
|
||||
}
|
||||
public void addVertex(String vname) {
|
||||
|
||||
vertex vtx=new vertex();
|
||||
this.vertcs.put(vname,vtx);
|
||||
}
|
||||
public void removeVertex(String vname) {
|
||||
vertex vtx=this.vertcs.get(vname);
|
||||
ArrayList<String> keys=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String key:keys) {
|
||||
vertex nbrvtx=this.vertcs.get(key);
|
||||
nbrvtx.nbrs.remove(vname);
|
||||
}
|
||||
this.vertcs.remove(vname);
|
||||
}
|
||||
|
||||
public int numEdge() {
|
||||
int count=0;
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
vertex vtx=this.vertcs.get(key);
|
||||
count+=vtx.nbrs.size();
|
||||
}
|
||||
return count/2;
|
||||
}
|
||||
public boolean containsEdge(String vname1,String vname2) {
|
||||
vertex vtx1=this.vertcs.get(vname1);
|
||||
vertex vtx2=this.vertcs.get(vname2);
|
||||
if(vtx1==null||vtx2==null||!vtx1.nbrs.containsKey(vname2))
|
||||
return false;
|
||||
return true;
|
||||
}
|
||||
public void addEdge(String vname1,String vname2,int cost) {
|
||||
vertex vtx1=this.vertcs.get(vname1);
|
||||
vertex vtx2=this.vertcs.get(vname2);
|
||||
if(vtx1==null||vtx2==null||vtx1.nbrs.containsKey(vname2))
|
||||
return;
|
||||
vtx1.nbrs.put(vname2,cost);
|
||||
vtx2.nbrs.put(vname1,cost);
|
||||
}
|
||||
public void removeEdge(String vname1,String vname2) {
|
||||
vertex vtx1=this.vertcs.get(vname1);
|
||||
vertex vtx2=this.vertcs.get(vname2);
|
||||
if(vtx1==null||vtx2==null||!vtx1.nbrs.containsKey(vname2))
|
||||
return;
|
||||
vtx1.nbrs.remove(vname2);
|
||||
vtx2.nbrs.remove(vname1);
|
||||
}
|
||||
|
||||
public void display() {
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
vertex vtx=this.vertcs.get(key);
|
||||
System.out.println(key+" := "+vtx.nbrs);
|
||||
}
|
||||
}
|
||||
|
||||
public boolean hasPath(String source ,String dest,HashMap<String,Boolean> processed) {
|
||||
processed.put(source, true);
|
||||
if(containsEdge(source,dest)) {
|
||||
return true;
|
||||
}
|
||||
vertex vtx=this.vertcs.get(source);
|
||||
ArrayList<String> keys=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String key:keys) {
|
||||
if(!processed.containsKey(key) && hasPath(key,dest,processed))
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
|
||||
}
|
||||
private class pair{
|
||||
String vname;
|
||||
String psf;
|
||||
}
|
||||
public boolean bfs(String source,String dest) { // breadth first search
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
|
||||
LinkedList<pair> queue=new LinkedList<>();
|
||||
pair sp=new pair();
|
||||
sp.vname=source;
|
||||
sp.psf=source;
|
||||
queue.addLast(sp);
|
||||
|
||||
while(!queue.isEmpty()) {
|
||||
pair rp=queue.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
if(containsEdge(rp.vname,dest)) {
|
||||
System.out.println(rp.psf+dest);
|
||||
return true;
|
||||
}
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
queue.addLast(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
public boolean dfs(String source,String dest) { //deapth first search
|
||||
LinkedList<pair> stack=new LinkedList<>();
|
||||
HashMap<String,Boolean> processed=new HashMap<>();
|
||||
pair sp=new pair();
|
||||
sp.vname=source;
|
||||
sp.psf=source;
|
||||
stack.addFirst(sp);
|
||||
while(!stack.isEmpty()) {
|
||||
pair rp=stack.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
if(containsEdge(rp.vname,dest)) {
|
||||
System.out.println(rp.psf+dest);
|
||||
return true;
|
||||
}
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String > nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
stack.addFirst(np);
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
return false;
|
||||
}
|
||||
public void bft() { //breadth first traversal
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
LinkedList<pair> queue=new LinkedList<>();
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
if(processed.containsKey(key))
|
||||
continue;
|
||||
pair sp=new pair();
|
||||
sp.vname=key;
|
||||
sp.psf=key;
|
||||
queue.addLast(sp);
|
||||
|
||||
while(!queue.isEmpty()) {
|
||||
pair rp=queue.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
System.out.println(rp.vname+" via "+rp.psf);
|
||||
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
queue.addLast(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
public void dft() { //deapt first traversal
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
LinkedList<pair> stack=new LinkedList<>();
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
pair sp=new pair();
|
||||
sp.vname=key;
|
||||
sp.psf=key;
|
||||
stack.addFirst(sp);
|
||||
|
||||
while(!stack.isEmpty()) {
|
||||
pair rp=stack.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
System.out.println(rp.vname+" via "+rp.psf);
|
||||
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
stack.addFirst(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
public boolean isCyclic() {
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
LinkedList<pair> queue=new LinkedList<>();
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
if(processed.containsKey(key))
|
||||
continue;
|
||||
pair sp=new pair();
|
||||
sp.vname=key;
|
||||
sp.psf=key;
|
||||
queue.addLast(sp);
|
||||
|
||||
while(!queue.isEmpty()) {
|
||||
pair rp=queue.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
return true;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
queue.addLast(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
public boolean isConnected() {
|
||||
int flag=0;
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
LinkedList<pair> queue=new LinkedList<>();
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
if(processed.containsKey(key))
|
||||
continue;
|
||||
flag++;
|
||||
pair sp=new pair();
|
||||
sp.vname=key;
|
||||
sp.psf=key;
|
||||
queue.addLast(sp);
|
||||
|
||||
while(!queue.isEmpty()) {
|
||||
pair rp=queue.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
queue.addLast(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
if(flag>=2)
|
||||
return false;
|
||||
else
|
||||
return true;
|
||||
}
|
||||
public boolean isTree() {
|
||||
return !isCyclic()&&isConnected();
|
||||
}
|
||||
public ArrayList<ArrayList<String>> getConnectedComp() {
|
||||
ArrayList<ArrayList<String>> ans=new ArrayList<>();
|
||||
HashMap<String ,Boolean> processed=new HashMap<>();
|
||||
LinkedList<pair> queue=new LinkedList<>();
|
||||
ArrayList<String> keys=new ArrayList<>(this.vertcs.keySet());
|
||||
for(String key:keys) {
|
||||
if(processed.containsKey(key))
|
||||
continue;
|
||||
ArrayList<String> subans=new ArrayList<>();
|
||||
pair sp=new pair();
|
||||
sp.vname=key;
|
||||
sp.psf=key;
|
||||
queue.addLast(sp);
|
||||
|
||||
while(!queue.isEmpty()) {
|
||||
pair rp=queue.removeFirst();
|
||||
if(processed.containsKey(rp.vname))
|
||||
continue;
|
||||
processed.put(rp.vname,true);
|
||||
|
||||
subans.add(rp.vname);
|
||||
|
||||
vertex vtx=this.vertcs.get(rp.vname);
|
||||
ArrayList<String> nbrs=new ArrayList<>(vtx.nbrs.keySet());
|
||||
for(String nbr:nbrs) {
|
||||
if(!processed.containsKey(nbr)) {
|
||||
pair np=new pair();
|
||||
np.vname=nbr;
|
||||
np.psf=rp.psf+nbr;
|
||||
queue.addLast(np);
|
||||
}
|
||||
}
|
||||
}
|
||||
ans.add(subans);
|
||||
}
|
||||
return ans;
|
||||
}
|
||||
private class PrimsPair implements Comparable<PrimsPair>{
|
||||
String vname;
|
||||
String acqvname;
|
||||
int cost;
|
||||
public int compareTo(PrimsPair o) {
|
||||
return o.cost-this.cost;
|
||||
}
|
||||
|
||||
}
|
||||
public Graph prims() {
|
||||
HashMap<String ,PrimsPair> map=new HashMap<>();
|
||||
GenericHeap<PrimsPair> heap=new GenericHeap<>();
|
||||
Graph mst=new Graph();
|
||||
for(String vrtx:this.vertcs.keySet()) {
|
||||
PrimsPair np=new PrimsPair();
|
||||
np.acqvname=null;
|
||||
np.vname=vrtx;
|
||||
np.cost=Integer.MAX_VALUE;
|
||||
heap.add(np);
|
||||
map.put(vrtx, np);
|
||||
}
|
||||
while(!heap.isEmpty()) {
|
||||
PrimsPair rp=heap.remove();
|
||||
map.remove(rp.vname);
|
||||
|
||||
if(rp.acqvname==null) {
|
||||
mst.addVertex(rp.vname);
|
||||
}else {
|
||||
mst.addVertex(rp.vname);
|
||||
mst.addEdge(rp.vname, rp.acqvname, rp.cost);
|
||||
}
|
||||
|
||||
for(String nbr:this.vertcs.get(rp.vname).nbrs.keySet()) {
|
||||
if(map.containsKey(nbr)) {
|
||||
//old cost that is from diff path stored in map
|
||||
int oc=map.get(nbr).cost;
|
||||
// cost that present vname need cost to go to nbr
|
||||
int nc=this.vertcs.get(rp.vname).nbrs.get(nbr);
|
||||
if(nc<oc) {
|
||||
PrimsPair gp=map.get(nbr);
|
||||
gp.acqvname=rp.vname;
|
||||
gp.cost=nc;
|
||||
heap.updatePriority(gp);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
||||
return mst;
|
||||
}
|
||||
|
||||
private class DijktsraPair implements Comparable<DijktsraPair>{
|
||||
String vname;
|
||||
String psf;
|
||||
int cost;
|
||||
public int compareTo(DijktsraPair o) {
|
||||
return o.cost-this.cost;
|
||||
}
|
||||
|
||||
}
|
||||
public HashMap<String,Integer> Dijktsra(String source) {
|
||||
HashMap<String ,DijktsraPair> map=new HashMap<>();
|
||||
GenericHeap<DijktsraPair> heap=new GenericHeap<>();
|
||||
HashMap<String,Integer> ans =new HashMap<>();
|
||||
for(String vrtx:this.vertcs.keySet()) {
|
||||
DijktsraPair np=new DijktsraPair();
|
||||
np.psf="";
|
||||
np.vname=vrtx;
|
||||
np.cost=Integer.MAX_VALUE;
|
||||
if(vrtx==source) {
|
||||
np.cost=0;
|
||||
np.psf=source;
|
||||
}
|
||||
heap.add(np);
|
||||
map.put(vrtx, np);
|
||||
}
|
||||
while(!heap.isEmpty()) {
|
||||
DijktsraPair rp=heap.remove();
|
||||
map.remove(rp.vname);
|
||||
|
||||
ans.put(rp.vname,rp.cost);
|
||||
|
||||
for(String nbr:this.vertcs.get(rp.vname).nbrs.keySet()) {
|
||||
if(map.containsKey(nbr)) {
|
||||
//old cost that is from diff path stored in map
|
||||
int oc=map.get(nbr).cost;
|
||||
// cost that present vname need cost to go to nbr
|
||||
int nc=rp.cost+this.vertcs.get(rp.vname).nbrs.get(nbr);
|
||||
if(nc<oc) {
|
||||
DijktsraPair gp=map.get(nbr);
|
||||
gp.psf=rp.psf+nbr;
|
||||
gp.cost=nc;
|
||||
heap.updatePriority(gp);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
||||
return ans;
|
||||
}
|
||||
|
||||
}
|
||||
Reference in New Issue
Block a user