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.