1 function Dijkstra(Graph, source): 2 3 create vertex set Q 4 5 for each vertex v in Graph: // Initialization 6 dist[v] ← INFINITY // Unknown distance from source to v 7 prev[v] ← UNDEFINED // Previous node in optimal path from source 8 add v to Q // All nodes initially in Q (unvisited nodes) 9 10 dist[source] ← 0 // Distance from source to source 11 12 while Q is not empty: 13 u ← vertex in Q with min dist[u] // Node with the least distance 14 // will be selected first 15 remove u from Q 16 17 for each neighbor v of u: // where v is still in Q. 18 alt ← dist[u] + length(u, v) 19 if alt < dist[v]: // A shorter path to v has been found 20 dist[v] ← alt 21 prev[v] ← u 22 23 return dist[], prev[]