Graph

Definition

A B
Graph G = (V, E), v,w V, (v,w) E
directed (v, w) is ordered
ajacent (v, w)
weight/cost edge
path w1, w2, …, wn, length n-1
loop (v, v)
simple path all vertices are distince, except first and last
cycle directed, w1 = wn
DAG directed acyclic graph
connected path from every vertex to other
strongly connected directed
weakly connected directed is not strongly connected, underlying graph is connected
complete graph edge between every vertices pair

Representation

A B space C
adjacency matricx A[u][v] = true/false/weight/Infinite O(|V| ^2) dense: | E| = O( | V | ^2)
adjacency list vertex -> a list of all adjacent vertices O(|E| + |V|) sparse: not dense
  • adjacency lists are the standard way to represent graphs

References