The probabilities assigned to all outcomes of a sample space must each lie in $[0, 1]$ and together sum to one:

$$\sum_{\omega \in \Omega} P(\omega) = 1$$

Return True if the list is a valid distribution, else False. Allow a tiny floating-point tolerance on the sum.

solve([0.5, 0.25, 0.25])  ->  True
solve([0.5, 0.6])         ->  False