From d0d6a0452af47b9699b360e95fe4e6532a996251 Mon Sep 17 00:00:00 2001
From: SaadAnsari17 <ansari.saadahmed07@gmail.com>
Date: Fri, 30 Sep 2022 22:39:03 +0530
Subject: [PATCH] Adding Prim's algorithm in graphs implemented in java

---
 algorithms/Java/graphs/Prims.java | 98 +++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 algorithms/Java/graphs/Prims.java

diff --git a/algorithms/Java/graphs/Prims.java b/algorithms/Java/graphs/Prims.java
new file mode 100644
index 00000000..96361c78
--- /dev/null
+++ b/algorithms/Java/graphs/Prims.java
@@ -0,0 +1,98 @@
+import java.lang.*;   
+import java.util.*;   
+import java.io.*;   
+  
+class Prims {   
+
+    private static final int countOfVertices = 9;   
+    
+    int findMinKeyVertex(int keys[], Boolean setOfMST[])   
+    {   
+        // Initialize min value and its index  
+        int minimum_index = -1;   
+        int minimum_value = Integer.MAX_VALUE;  
+          
+        //iterate over all vertices to find minimum key-value vertex  
+        for (int vertex = 0; vertex < countOfVertices; vertex++)   
+            if (setOfMST[vertex] == false && keys[vertex] < minimum_value) {   
+                minimum_value = keys[vertex];   
+                minimum_index = vertex;   
+            }   
+    
+        return minimum_index;   
+    }   
+    
+    void showMinimumSpanningTree(int mstArray[], int graphArray[][])   
+    {   
+        System.out.println("Edge \t\t Weight");   
+        for (int j = 1; j < countOfVertices; j++)   
+            System.out.println(mstArray[j] + " <-> " + j + "\t \t" + graphArray[j][mstArray[j]]);   
+    }   
+    
+    void designMST(int graphArray[][])   
+    {   
+        int mstArray[] = new int[countOfVertices];   
+    
+        int keys[] = new int[countOfVertices];   
+    
+        Boolean setOfMST[] = new Boolean[countOfVertices];   
+    
+        for (int j = 0; j < countOfVertices; j++) {   
+            keys[j] = Integer.MAX_VALUE;   
+            setOfMST[j] = false;   
+        }   
+    
+        keys[0] = 0; 
+        mstArray[0] = -1; 
+    
+        for (int i = 0; i < countOfVertices - 1; i++) {   
+
+            int edge = findMinKeyVertex(keys, setOfMST);   
+    
+            setOfMST[edge] = true;   
+    
+            for (int vertex = 0; vertex < countOfVertices; vertex++)   
+    
+                if (graphArray[edge][vertex] != 0 && setOfMST[vertex] == false && graphArray[edge][vertex] < keys[vertex]) {   
+                    mstArray[vertex] = edge;   
+                    keys[vertex] = graphArray[edge][vertex];   
+                }   
+        }   
+    
+        showMinimumSpanningTree(mstArray, graphArray);   
+    }   
+    public static void main(String[] args)   
+    {   
+          
+        Prims mst = new Prims();   
+        int graphArray[][] = new int[][]{{ 0, 4, 0, 0, 0, 0, 0, 8, 0 },   
+                    { 4, 0, 8, 0, 0, 0, 0, 11, 0 },   
+                    { 0, 8, 0, 7, 0, 4, 0, 0, 2 },   
+                    { 0, 0, 7, 0, 9, 14, 0, 0, 0 },   
+                    { 0, 0, 0, 9, 0, 10, 0, 0, 0 },  
+                    { 0, 0, 4, 14, 10, 0, 2, 0, 0 },  
+                    { 0, 0, 0, 0, 0, 2, 0, 1, 6 },  
+                    { 8, 11, 0, 0, 0, 0, 1, 0, 7 },  
+                    { 0, 0, 2, 0, 0, 0, 6, 7, 0 }};   
+    
+        mst.designMST(graphArray);   
+    }   
+}  
+
+
+
+/* 
+
+-> Output 
+
+Edge             Weight
+0 <-> 1         4
+1 <-> 2         8
+2 <-> 3         7
+3 <-> 4         9
+2 <-> 5         4
+5 <-> 6         2
+6 <-> 7         1
+2 <-> 8         2
+
+*/