stack that is fast for push, pop and min

stack_test.groovy

l = []
l2 = []

def push(def num) {
   if (l) {
      l2 << ( (l[l.size() - 1] < num)  ? l[l.size() -1] : num )
   } else {
       l2 << num
   }
   l << num
}

def pop() {
  def ret = l[l.size() - 1]
  l.remove(l.size() -1) 
  l2.remove(l2.size() - 1)
  return ret
}

def min() {
  l2[l.size() -1]
}

push(6); push(3); push(7)
printit()
println "min " + min()
def printit() {
println l
println l2
}

println "pop " + pop()
println min()
println "pop " + pop()
println min()
println l2