In graph theory, the $complement$ of a graph $ G $ is a graph $ H $ on the same vertices such that two distinct vertices of $ H $ are adjacent if and only if they are $not$ adjacent in $ G $.
Now you are given an undirected graph $ G $ of $ N $ nodes and $ M $ bidirectional edges of $unit$ length. Consider the complement of $G$, i.e., $H$. For a given vertex $ S $ on $ H $, you are required to compute the shortest distances from $ S $ to all $ N-1 $ other vertices.