public static List> distrib( int n, int k, int p ) { if (p > n) return new ArrayList>(); if (k ==1) return new ArrayList>(){{add(new ArrayList(){{add(String.valueOf(n));}});}}; List> L1 = distrib(n,k,p+1); List> L2 = distrib(n-p,k-1,0); for (List list : L2) list.add(String.valueOf(p)); L1.addAll(L2); return L1; }

Explain in plain English the logic for enumerating distributions.