• Output of the Dijkstra algo is a spanning tree. We will prove that the generated tree is a MST

Proof

  • By contradiction: assume the algo outputs an expensive tree
  • If the algo doesn’t work, then at some point, it will reach a point where it does a mistake
    • we will prove that this mistake is actually not a mistake and the ‘mistake’ is actually no worse than the optimal solution
  • 30
  • There must be a cycle and a green edge
  • Because the algo picks an edge of least cost
    • no worse than the optimal solution
    • is acc better coz