Python implementation of kruskal's algo

02. Algorithms/05. Graphs/Minimum Spanning Tree/Kruskal Algorithm/kruskals_algo.py

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+'''
+Kruskals algo implementation 
+'''
+from collections import defaultdict, deque
+
+class Kruskals:
+def __init__(self, v):
+self.vertices = v
+self.graph = []
+self.parent = [-1] * self.vertices
+self.rank = [0] * self.vertices
+self.min_cost = 0
+self.mst = []
+
+def add_edge(self, src, dest, weight):
+self.graph.append((src, dest, weight))
+
+def make_set(self):
+for i in range(self.vertices):
+self.parent[i] = i
+
+def find_parent(self, node):
+if node == self.parent[node]:
+return node
+
+return self.find_parent(self.parent[node])
+
+def union(self, src, dest):
+src = self.find_parent(src)
+dest = self.find_parent(dest)
+
+if self.rank[src] < self.rank[dest]:
+self.parent[src] = dest
+elif self.rank[dest] < self.rank[src]:
+self.parent[dest] = src
+else:
+self.parent[dest] = src
+self.rank[src] += 1
+
+
+def construct_mst(self):
+# sorting the graph by edge weights
+self.graph.sort(key = lambda x: x[2])
+
+for node in self.graph:
+src = node[0]
+dest = node[1]
+w = node[2]
+if self.find_parent(src) != self.find_parent(dest):
+self.min_cost += w
+# storing the nodes src and dest forming mst
+self.mst.append((src, dest))
+
+# performing union operation
+self.union(src, dest)
+
+print('MST ->', self.mst)
+print('Minimum cost for MST ->', self.min_cost)
+
+
+if __name__ == '__main__':
+g = Kruskals(5)
+
+g.add_edge(0, 1, 2) # src, dest, weight
+g.add_edge(0, 3, 6)
+g.add_edge(1, 0, 2)
+g.add_edge(1, 2, 3)
+g.add_edge(1, 3, 8)
+g.add_edge(1, 4, 5)
+g.add_edge(2, 1, 3)
+g.add_edge(2, 4, 7)
+g.add_edge(3, 0, 6)
+g.add_edge(3, 1, 8)
+g.add_edge(4, 1, 5)
+g.add_edge(4, 2, 7)
+
+g.make_set()
+g.construct_mst()
+
+