Kruskal Minimum Spanning Tree

Problem

Given n nodes and undirected weighted edges as [u, v, w] triples, return the total weight of a minimum spanning tree, or -1 if the graph is disconnected.

Sort edges by weight and add each edge whose endpoints lie in different union-find components, stopping after n - 1 edges. A single node has an empty spanning tree of weight 0.

Hint

A minimum spanning tree on n nodes uses exactly n - 1 edges.

Test cases

case 1

in: [4,[[0,1,1],[0,2,4],[1,2,2],[1,3,5],[2,3,3]]]

expected: 6

case 2

in: [1,[]]

expected: 0

case 3

in: [3,[[0,1,1]]]

expected: -1

case 4

in: [4,[[0,1,1],[1,2,2],[2,3,3],[0,3,10],[1,3,5]]]

expected: 6

case 5

in: [2,[[0,1,7]]]

expected: 7

Starter codePython

def kruskal_mst(n, edges):
    # Your code here
    pass

5 test cases · run your code against them in the editor