Skip to content

MST Ladder

MST practice should build the instinct that “connect everything cheaply” is a different goal from shortest paths, and that Kruskal is really a sorted greedy plus DSU invariant.

Who This Is For

Use this ladder if:

  • weighted graph problems still blur together
  • Kruskal feels like a memorized recipe instead of a justified greedy
  • you forget to check whether the graph is actually connectable

Warm-Up

  • Kruskal on small undirected graphs
  • detect whether all vertices become connected

Target skill:

  • understand why each chosen edge is safe

Core

  • MST with DSU
  • compare Kruskal and Prim

Target skill:

  • choose the algorithm from the graph representation and proof style

Stretch

  • threshold or clustering problems built on MST
  • use MST edges for later reasoning about bottlenecks

Target skill:

  • treat MST as a reusable subroutine, not just a standalone task

Exit Criteria

You are ready to move on when:

  • you can explain the cut-property intuition in plain language
  • you never confuse MST with shortest paths
  • you remember to verify full connectivity

External Practice