title: Is there a R package for solving -1/0/1 knapsack?
body: <p>Is there an efficient R-package for dealing with the following problem:</p>
  
  <p>I have a set of numerical observations (N in the order of thousands) ranging from -one million to +one million. Given a target value and round off accurarcy is there a linear combination with weights -1(subtract)/0(leave out)/1(add up) such that the sum is equal to the target value within rounding errors and also presenting the weights?</p>