Merge pull request codemistic#603 from Lokesh-Choudhary/patch-2

Kruskal's_Algorithm.py

Author: gantavyamalviya

Python/Kruskal's_Algorithm.py

@@ -0,0 +1,69 @@
+# Kruskal's algorithm in Python
+
+
+class Graph:
+ def __init__(self, vertices):
+ self.V = vertices
+ self.graph = []
+
+ def add_edge(self, u, v, w):
+ self.graph.append([u, v, w])
+
+ # Search function
+
+ def find(self, parent, i):
+ if parent[i] == i:
+ return i
+ return self.find(parent, parent[i])
+
+ def apply_union(self, parent, rank, x, y):
+ xroot = self.find(parent, x)
+ yroot = self.find(parent, y)
+ if rank[xroot] < rank[yroot]:
+ parent[xroot] = yroot
+ elif rank[xroot] > rank[yroot]:
+ parent[yroot] = xroot
+ else:
+ parent[yroot] = xroot
+ rank[xroot] += 1
+
+ # Applying Kruskal algorithm
+ def kruskal_algo(self):
+ result = []
+ i, e = 0, 0
+ self.graph = sorted(self.graph, key=lambda item: item[2])
+ parent = []
+ rank = []
+ for node in range(self.V):
+ parent.append(node)
+ rank.append(0)
+ while e < self.V - 1:
+ u, v, w = self.graph[i]
+ i = i + 1
+ x = self.find(parent, u)
+ y = self.find(parent, v)
+ if x != y:
+ e = e + 1
+ result.append([u, v, w])
+ self.apply_union(parent, rank, x, y)
+ for u, v, weight in result:
+ print("%d - %d: %d" % (u, v, weight))
+
+
+g = Graph(6)
+g.add_edge(0, 1, 4)
+g.add_edge(0, 2, 4)
+g.add_edge(1, 2, 2)
+g.add_edge(1, 0, 4)
+g.add_edge(2, 0, 4)
+g.add_edge(2, 1, 2)
+g.add_edge(2, 3, 3)
+g.add_edge(2, 5, 2)
+g.add_edge(2, 4, 4)
+g.add_edge(3, 2, 3)
+g.add_edge(3, 4, 3)
+g.add_edge(4, 2, 4)
+g.add_edge(4, 3, 3)
+g.add_edge(5, 2, 2)
+g.add_edge(5, 4, 3)
+g.kruskal_algo()