Failed constraint solving invocation seems to affect subsequent runs

[Woosuk Kwak (Bubbler)]

I have a following code which is meant to solve Project Euler 34 (finding numbers which are equal to the sum of their digits’ factorials). In particular, find_sols(N) returns all solutions of digit length N.

import cp. find_sols(N) = solve_all(Num) => A :: 1..9, Rest = new_list(N - 1), Rest :: 0..9, Digits = [A|Rest], Facs = new_list(N), foreach ({D, F} in zip(Digits, Facs)) element0(D, [1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880], F) end, Reducer = new_list(N), Reducer[1] #= A, foreach (I in 2..N) Reducer[I] #= Reducer[I-1] * 10 + Digits[I] end, Num #= Reducer[N], sum(Facs) #= Num. sol = [find_sols(3), find_sols(5)].

Here sol() gives [[145], [40585]].

The problem is, if I replace the last line with [find_sols(3), find_sols(4), find_sols(5)] then the answer for 5 digits disappears and I get [[145], [], []]. Is this a bug or expected behavior?

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