http://expert.9cbs.net/expert/topic/3105/3105509.xml?temp=.1253168
Compared with another algorithm of the author (http://www.9cbs.net/develop/read_article.asp?id=28306), the following method is used, and the calculation speed of the class is several times!
Sub CalcFactorial (byval n as integer) Dim xys () AS INTEGER, X () AS Integer, y () AS integer, result () AS STRING, I As Long, J AS Long, K As Long, Temp As long, Stimer As Doubleif N <0 THEN EXIT SUBREDIM X (1) Redim Xys (1) x (1) = 1xys (1) = 1k = 1stimer = Timerdo While K <= n
Temp = LEN (CSTR (K)) Redim Y (1 to Temp) for i = 1 to Tempy (i) = VAL (MID (K, I, 1)) Nextredim Xys (LBound (x) to Ubound (x) Ubound (y) for i = lbound (x) to ubound (x) for j = 1 to uBound (y) XYS (i j) = xys (i j) x (i) * y (j) NextNextFor I = ubound (x) ubound (y) to lbound (x) 1 step -1temp = xys (i) / 10XYS (i) = xys (i) mod 10XYS (i - 1) = xys (i - 1) TempNext
X = xysk = k 1loop
Redim Result (1 to Ubound (x)) i = 1
Do While X (I) = 0 'Eliminates the result of multiple "0" Result (i) = "" "" I = i 1LoOopdo while not i> Ubound (x) Result (i) = x (i) i = i 1LOOPFACTORIAL = JOIN (Result, ") Debug.print K - 1 &"!: Time "; Timer - Stimer &" Second, Result "& Len (Factorial) &" Bit "'Debug.Print Factorialerase x () ERASE Y () Erase Xys () ERASE RESULT () End Sub
PRIVATE SUB Command1_Click () for i = 1 to 10calcfactorial i * 1000Next
End Sub
During the above process, the array of calculation results of each step, the beginning of the number of "0", resulting in the waste of time and memory resources, and the larger value, the more invalid operations. Work hard thinking more effectively, please advise the algorithm.
Output results:
100! : Time .015625 seconds, result 158 bits 200! : Time .047124999997322 seconds, 375 bits 300! : When used. 172625000000006519 seconds, 615 bits 400! : When used. 266250000000582 seconds, 869 bits 500! : When used .42274999997905 seconds, 1135 bits 600! : When used. 657000000006519 seconds, the result 1409 bit 700! : Time. 891250000000582 seconds, 1690 bits 800! : When used, 1.1571249999979 seconds, the result 1977 bit 900! : When used, 1.48450000000594 seconds, the result 2270 bit 1000! : When used, 1.84412500000000326 seconds, the result 2568 bits 2000! : Time 9.79700000000594 seconds, 5736 bits 3000! : 23.703125 seconds, the result 9131 bits 4000! : Use 43.7663750000065 seconds, the result 12674 bits 5000! : 72.0003750000000033 seconds, 16326 bits 6000! : Take 104.15625 seconds, 20066 bit 7000! : Time 142.422749999998 seconds, 30878 bits 8000! : When used 192.125375000003 seconds, the result 27753 bit 9000! : When used, 241.281875000001 seconds, the result 31682 bits 10000! : 32.859500000006 seconds, 35660
5000! =
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