Data commit

Task/Average-loop-length/Lua/average-loop-length.lua

@@ -0,0 +1,26 @@
+function average(n, reps)
+  local count = 0
+  for r = 1, reps do
+    local f = {}
+    for i = 1, n do f[i] = math.random(n) end
+    local seen, x = {}, 1
+    while not seen[x] do
+      seen[x], x, count = true, f[x], count+1
+    end
+  end
+  return count / reps
+end
+
+function analytical(n)
+  local s, t = 1, 1
+  for i = n-1, 1, -1 do t=t*i/n s=s+t end
+  return s
+end
+
+print(" N    average    analytical    (error)")
+print("===  =========  ============  =========")
+for n = 1, 20 do
+  local avg, ana = average(n, 1e6), analytical(n)
+  local err = (avg-ana) / ana * 100
+  print(string.format("%3d  %9.4f  %12.4f  (%6.3f%%)", n, avg, ana, err))
+end