Given a list of song durations, split them into two parts of equal length using knapsack

knapsack.R

# given a list of song durations, split them into two parts of equal length using knapsack

songs=list("drugs"=6*60+40,"error"=5*60+36,"stepvhen"=5*60+17,"infinity"=6*60+13,
       "pete"=2*60+38,"Zalh"=7*60+3,"morpheus"=5*60+4,"cleartone"=6*60+5,
       "dedmeth"=6*60+32,"orthodox"=2*60+18,"xeph"=4*60+12,"amelia where are"=6*60+58)



half.cassette <- local (
  function (target) {
      c <- gtools::combinations(length(songs), r=6, v=unlist(songs))
      s=rowSums(c)
      x <- which( abs(s-target) < 2 )
      c[x,]
  })

half.cassette(sum(unlist(songs))/2)