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| 1 | +//Prim's Algo to calculate the minimum spanning tree with user-input, using the Fibonacci Heap Method. |
| 2 | + |
| 3 | +import sys |
| 4 | +import heapq |
| 5 | + |
| 6 | +class UniqueGraph: |
| 7 | + def __init(self, vertices_count): |
| 8 | + self.V = vertices_count |
| 9 | + self.edges = [[] for _ in range(vertices_count)] |
| 10 | + |
| 11 | + def find_min_edge(self, key_values, mst_set): |
| 12 | + min_value = sys.maxsize |
| 13 | + min_index = 0 |
| 14 | + |
| 15 | + for vertex in range(self.V): |
| 16 | + if key_values[vertex] < min_value and not mst_set[vertex]: |
| 17 | + min_value = key_values[vertex] |
| 18 | + min_index = vertex |
| 19 | + |
| 20 | + return min_index |
| 21 | + |
| 22 | + def find_minimum_spanning_tree(self): |
| 23 | + parents = [None] * self.V |
| 24 | + key_values = [sys.maxsize] * self.V |
| 25 | + key_values[0] = 0 |
| 26 | + mst_set = [False] * self.V |
| 27 | + |
| 28 | + parents[0] = -1 |
| 29 | + min_heap = [(0, 0)] |
| 30 | + |
| 31 | + while min_heap: |
| 32 | + current_value, current_vertex = heapq.heappop(min_heap) |
| 33 | + mst_set[current_vertex] = True |
| 34 | + |
| 35 | + for edge in self.edges[current_vertex]: |
| 36 | + adjacent_vertex, weight = edge |
| 37 | + if not mst_set[adjacent_vertex] and key_values[adjacent_vertex] > weight: |
| 38 | + key_values[adjacent_vertex] = weight |
| 39 | + parents[adjacent_vertex] = current_vertex |
| 40 | + heapq.heappush(min_heap, (key_values[adjacent_vertex], adjacent_vertex)) |
| 41 | + |
| 42 | + self.print_minimum_spanning_tree(parents, key_values) |
| 43 | + |
| 44 | + def print_minimum_spanning_tree(self, parents, key_values): |
| 45 | + print("Edge \tWeight") |
| 46 | + for vertex in range(1, self.V): |
| 47 | + print(f"{parents[vertex]} - {vertex}\t{key_values[vertex]}") |
| 48 | + |
| 49 | +# Input the graph from the user |
| 50 | +V = int(input("Enter the number of vertices: ")) |
| 51 | +g = UniqueGraph(V) |
| 52 | +print("Enter the edges and their weights (e.g., '1 2 3' means an edge from vertex 1 to vertex 2 with weight 3):") |
| 53 | + |
| 54 | +for _ in range(V - 1): |
| 55 | + u, v, w = map(int, input().split()) |
| 56 | + g.edges[u].append((v, w)) |
| 57 | + g.edges[v].append((u, w)) |
| 58 | + |
| 59 | +g.find_minimum_spanning_tree() |
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