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BM40A1500 Data Structures and Algorithms/Assignments/Week 10/kruskal.py

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+from graph import Graph
+
+
+def kruskal(graph: Graph):
+    matrix = graph.matrix
+    V = graph.V
+    edges = []
+    for i in range(V):
+        for j in range(V):
+            if matrix[i][j] > 0:
+                edges.append((i, j, matrix[i][j]))
+    edges.sort(key=lambda item: item[2])
+    subsets = []
+    for i in range(V):
+        subsets.append([i])
+    result = []
+    for edge in edges:
+        subset1 = None
+        subset2 = None
+        for subset in subsets:
+            if edge[0] in subset:
+                subset1 = subset
+            if edge[1] in subset:
+                subset2 = subset
+        if subset1 != subset2:
+            result.append(edge)
+            subsets.remove(subset1)
+            subsets.remove(subset2)
+            subsets.append(subset1 + subset2)
+    new_matrix = [[0] * V for _ in range(V)]
+    for edge in result:
+        new_matrix[edge[0]][edge[1]] = edge[2]
+        new_matrix[edge[1]][edge[0]] = edge[2]
+    return Graph(new_matrix)
+
+
+if __name__ == "__main__":
+    matrix = [
+        #    0  1  2  3  4  5
+        [0, 0, 7, 6, 9, 0],  # 0
+        [0, 0, 5, 0, 0, 6],  # 1
+        [7, 5, 0, 1, 0, 2],  # 2
+        [6, 0, 1, 0, 0, 2],  # 3
+        [9, 0, 0, 0, 0, 1],  # 4
+        [0, 6, 2, 2, 1, 0]  # 5
+    ]
+    graph = Graph(matrix)
+    graph.bf_print(0)   # 0 2 3 4 1 5
+    mst = kruskal(graph)
+    mst.bf_print(0)     # 0 3 2 1 5 4