B

Task/Average-loop-length/BBC-BASIC/average-loop-length.bbc

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+      @% = &2040A
+      MAX_N = 20
+      TIMES = 1000000
+
+      FOR n = 1 TO MAX_N
+        avg = FNtest(n, TIMES)
+        theory = FNanalytical(n)
+        diff = (avg / theory - 1) * 100
+        PRINT STR$(n), avg, theory, diff "%"
+      NEXT
+      END
+
+      DEF FNanalytical(n)
+      LOCAL i, s
+      FOR i = 1 TO n
+        s += FNfactorial(n) / n^i / FNfactorial(n-i)
+      NEXT
+      = s
+
+      DEF FNtest(n, times)
+      LOCAL i, b, c, x
+      FOR i = 1 TO times
+        x = 1 : b = 0
+        WHILE (b AND x) = 0
+          c += 1
+          b OR= x
+          x = 1 << (RND(n) - 1)
+        ENDWHILE
+      NEXT
+      = c / times
+
+      DEF FNfactorial(n)
+      IF n=1 OR n=0 THEN =1 ELSE = n * FNfactorial(n-1)