prims algorithm greedy method.py

greedy_methods/prims algorithm greeedy method.py

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+def prims_algorithm(n, cost):
+    visited = [0] * (n + 1)  # Initialize visited array
+    visited[1] = 1  # Start from the first vertex
+    mincost = 0
+    ne = 1  # Number of edges in the spanning tree
+
+    print("The edges of the spanning tree are:")
+
+    while ne < n:
+        min_cost = float('inf')
+        a = u = b = v = -1  # Initialize variables
+
+        for i in range(1, n + 1):
+            for j in range(1, n + 1):
+                if cost[i][j] < min_cost:
+                    if visited[i] == 0:
+                        continue
+                    else:
+                        min_cost = cost[i][j]
+                        a = u = i
+                        b = v = j
+
+        if visited[u] == 0 or visited[v] == 0:
+            print(f"{ne}: edge({a}, {b}) = {min_cost}\t")
+            mincost += min_cost
+            visited[b] = 1
+            ne += 1
+
+        cost[a][b] = cost[b][a] = float('inf')  # Mark the edge as processed
+
+    print(f"\nMinimum cost is {mincost}")
+
+
+if __name__ == "__main__":
+    n = int(input("Enter the number of vertices in the graph: "))
+    cost = [[0] * (n + 1) for _ in range(n + 1)]
+
+    print("Enter the cost matrix of the graph:")
+    for i in range(1, n + 1):
+        for j in range(1, n + 1):
+            if i == j:
+                cost[i][j] = 0  # No self-loop
+            else:
+                cost[i][j] = int(input(f"({i},{j}): "))
+                if cost[i][j] == 0:
+                    cost[i][j] = float('inf')  # Use inf for no connection
+
+    prims_algorithm(n, cost)