In finding the shortest path, which vertex is used as a reference point?

The start vertex, often denoted as S, serves as a crucial reference point in finding the shortest path in a graph. When applying algorithms such as Dijkstra's or Bellman-Ford, the process begins at this vertex and explores paths to reach other vertices in the graph. The primary aim is to calculate the shortest distance from the start vertex to all other connected vertices.

Choosing the start vertex allows for systematic exploration, ensuring that all possible paths are evaluated, and the minimum distance is determined. The other choices do not provide a logical basis for initiating the search for the shortest path. For example, the finish vertex, or any random vertex, would not establish a clear starting point for measurement, and using a vertex with the largest edge weight contradicts the objective of finding the shortest path. Thus, the start vertex is the fundamental reference point needed to accurately determine the shortest distances across the graph.