Problem 45219. Find edges from a vertex

First input is T, a triplet list of indices. Second input is i, a single index (positive integer). The goal of this function is to find and return all the edges [e1 e2] this vertex belong to.
For example if inputs are
T = [1 2 3 ;...
1 3 4 ;...
1 4 2 ;...
2 3 4]
and
i = 4
then the output is the 3 x 2
matrix edg_list= [1 4;...
3 4;...
2 4]
since vertex number 4 is linked with vertices number 1, 2, and 3 and then part of edges [1 4], [2 4], and [3 4]. Format of the output must be the following :
  • size(edg_list) = [number of edges, 2]
  • Every row of it is an edge at the format [e1, e2], sorted in ascending order, i.e. e1 < e2, and e1, e2 positive integers.
  • Each edge is present once and only once, no duplicated edge admitted
  • Order of rows / edges in the output doesn't matter .
If the vertex is not in the list, the function must of course return the empty set.
See also
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Solution Stats

38.1% Correct | 61.9% Incorrect
Last Solution submitted on Nov 18, 2025

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