AIZU ONLINE JUDGE: Programming Challenge 0041 Expression def solve(ary) if ary.size <= 1 return ary[0] if eval(ary[0]) == 10 else idxs = [*0...ary.size] idxs.combination(2) do |i, j| a, b = ary[i], ary[j] nxt = (idxs - [i, j]).map{|x| ary[…