Truthify an array
Jelly has an atom called untruth, which when given indices, creates an array with 1s at those places:
[2,4] → [0,1,0,1].
You are required to perform the inverse of this. Given a 2D boolean array, find the indices of the true values in it.
You will be given a single 2D boolean array $M$. You may take its dimensions as a separate argument if needed.
The output must consist of all the indices of the true values in $M$.
Output may be 0-indexed or 1-indexed.
It is guaranteed that the input will only consist of two different values.
All test cases are 0-indexed.
I: [[1,0,1,1,1,0]] O: [[0,0],[0,2],[0,3],[0,4]] I: [[1,0,1],[1,0,1],[0,1,0]] O: [[0,0],[0,2],[1,0],[1,2],[2,1]]
[APL (Dyalog Extended)], 1 byt …
[Jelly], 2 bytes ŒṪ …
[C (gcc)], 100 bytes …