Solution: If the list of items is empty, then the best that can be done is a sum of 0. If the list of items is non-empty, then if the first item is larger than the goal, it cannot be included. Otherwise, solve the problem recursively under two disjoint assumtions: that the first item is included or it is not.

pick(Goal, []) => [0, []]; // empty list can only meet goal 0 

pick(Goal, [Item | Items]) => 

  Item > Goal ? pick(Goal, Items) // Item too large to use 

: [Sum1, Items1] = pick(Goal-Item, Items), // Try with Item 

  [Sum2, Items2] = pick(Goal, Items), // Try without Item 

  Sum1 + Item > Sum2 ? // Which is closer? 

    [Sum1+Item, [Item | Items1]] // Using item 

  : [Sum2, Items2]; // Not using item