prims-mst-algo

Author: aakankshabhende

Greedy/Prim’s Minimum Spanning Tree.cpp

@@ -0,0 +1,89 @@
+// Program to calculate Minimum Spanning Tree using Prim's algorithm in C++.
+#include <iostream>
+#include <conio.h>
+#define ROW 7
+#define COL 7
+#define INFINITY 5000
+using namespace std;
+class MST
+{
+    int graph[ROW][COL], nodes, mini;
+
+public:
+    MST();
+    void createGraph();
+    void primsAlgo();
+};
+
+MST ::MST()
+{
+    for (int i = 0; i < ROW; i++)
+        for (int j = 0; j < COL; j++)
+            graph[i][j] = 0;
+}
+
+void MST ::createGraph()
+{
+    int i, j;
+    cout << "Enter Total Nodes : ";
+    cin >> nodes;
+    cout << "\nEnter Adjacency Matrix : \n";
+    for (i = 0; i < nodes; i++)
+        for (j = 0; j < nodes; j++)
+            cin >> graph[i][j];
+
+    for (j = 0; j < nodes; j++)
+    {
+        if (graph[i][j] == 0)
+            graph[i][j] = INFINITY;
+    }
+}
+
+void MST ::primsAlgo()
+{
+    int selected[ROW], i, j, nos_of_edges, x, y;
+
+    for (i = 0; i < nodes; i++)
+        selected[i] = false;
+
+    selected[0] = true;
+    nos_of_edges = 0;
+
+    while (nos_of_edges < nodes - 1)
+    {
+        mini = INFINITY;
+
+        for (i = 0; i < nodes; i++)
+        {
+            if (selected[i] == true)
+            {
+                for (j = 0; j < nodes; j++)
+                {
+                    if (selected[j] == false)
+                    {
+                        if (mini > graph[i][j])
+                        {
+                            mini = graph[i][j];
+                            x = i;
+                            y = j;
+                        }
+                    }
+                }
+            }
+        }
+        selected[y] = true;
+        cout << "\n"
+             << x + 1 << " --> " << y + 1;
+        nos_of_edges = nos_of_edges + 1;
+    }
+}
+
+int main()
+{
+    MST a;
+    cout << "\nPrims Algorithm to find Minimum Spanning Tree\n";
+    a.createGraph();
+    a.primsAlgo();
+    getch();
+    return 0;
+}