Kruskal's algorithm

Kruskal's algoritm computes the shortest spanning tree in a graph.

It works as follows:

1. sort the edges by length in ascending order
2. take the first edge of this list and add it to the tree
3. if you have reached the end of the list, stop
4. consider the next edge on the list: if it will form a cycle when added to the tree, discard it; otherwise add it to the tree
5. go back to step 3