Difficulty: Medium · Puzzle 5 of 6 · Topic: Constraint Solving Order Puzzles
Find all legal (a,b) pairs and compute P(a==0).
class pair_rel;
rand int unsigned a;
rand int unsigned b;
constraint c {
a inside {[0:6]};
b inside {[0:6]};
a < b;
a + b == 6;
}
endclassEnumerate integer pairs that sum to 6, then apply a<b.
1) Candidate pairs in 0..6 with sum 6 are (0,6),(1,5),(2,4),(3,3),(4,2),(5,1),(6,0).
2) Apply a<b -> keep (0,6),(1,5),(2,4).
3) Legal tuple count=3 and one tuple has a==0.
4) So P(a==0)=1/3.Answer: Legal tuples are (0,6),(1,5),(2,4), so P(a==0)=1/3 (~33.33%).
Candidates often enforce a<=b by mistake and incorrectly keep (3,3).
If you add solve a before b, does legality change? What might shift in observed solver bias?