# Dynamic programming comparing recursive----to Fibonacci sequence for example

Source: Internet
Author: User

Here's how it's recursive:

`Private Static int Fib_re (int  N)        {            Re_count++            ; if (n<=1)            {                return1;            }             Else             {                return fib_re (n1) + fib_re (n-2);}        }`

Here is the dynamic plan:

`Private Static int Fib_fast (int n,dictionary<intint> dic)        {            Fa_count++            ; if (! DiC. ContainsKey (n))            {                dic. ADD (n, fib_fast (n-1, DIC) +fib_fast (n-2, dic);            }             return dic[n];        }`

Test process:

`            Const intNUM = +; Stopwatch SW=NewStopwatch (); Sw.            Start (); intResult_re =fib_re (NUM); Sw.            Stop (); Console.WriteLine ("fib_re ({0}) ={1}: Time: {2}, Times: {3}", Num,result_re, SW.            Elapsedticks, Re_count); Sw.            Reset (); Sw.            Start (); Dictionary<int,int> dic =Newdictionary<int,int>(); Dic. ADD (0,1); Dic. ADD (1,1); intRESULT_FA =Fib_fast (num,dic); Sw.            Stop (); Console.WriteLine ("Fib_fast ({0}) ={1}: Time: {2}, Times: {3}", NUM,RESULT_FA, SW. Elapsedticks, Fa_count);`

Results:

Time is nearly 20,000 times times ...

Dynamic programming comparing recursive----to Fibonacci sequence for example

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