#!/home/craigd/Bin/zkl
collatz:=Import("hailstone",False,False,False).collatz; // don't run constructor
d:=Dictionary();
[2..0d100_000].pump(Void,  // loop n from 2 to 100,000
   collatz,       // generate Collatz sequence(n)
   'wrap(c){ d.incV(c.len()) }      // save length
);
println("Number of different lengths: ",d.len());
longest:=(0).max(d.values);
mostFreqLen:=d.filter1('wrap([(k,v)]){ v==longest })[0];
println("Most frequent length: %d; %d sequences of that length."
        .fmt(mostFreqLen,longest));