How to make Mathematica re-evaluate a cell after some event?

Question

I am doing a little project to demonstrate something:

a = 2; b = 5000; 
d = 10000; l1 = {};  
rc := RandomChoice[{a, b} -> {0, 1}]
c = 1; While[c <= d, AppendTo[l1, rc];c++] 
e = ((Count[l1, _] - Count[l1, 0])/d)*100//N 
f = 100 - e

I want to insert two InputFields for the values of A and B, but I want it to re-evaluate the rest of the cell whenever I input new values for A and B - I'm also curious for A or B.

Note - Inserting the inputfields is not my problem, my problems is only the reevaluation of the cell after some event.

Answer 1

The simplest solution IMHO is using Manipulate. Almost no change in your code is necessary:

Manipulate[
 d = 10000; l1 = {};
 rc := RandomChoice[{a, b} -> {0, 1}];
 c = 1; While[c <= d, AppendTo[l1, rc]; c++];
 Column[
  {
   e = ((Count[l1, _] - Count[l1, 0])/d)*100 // N,
   f = 100 - e
   }
  ],
 {a, 2}, {b, 5000},
 TrackedSymbols -> {a, b}
 ]

Answer 2

Using DynamicModule (note that I modified some of your default values to give a more intuitive output):

   DynamicModule[{a = 2, b = 5, d = 30, update, e, f, temp = 1, rc, l1},

 Grid[{
   {"weight of 0 (a)", InputField[Dynamic[a, (a = #; update[]) &]]},
   {"weight of 1 (b)", InputField[Dynamic[b, (b = #; update[]) &]]},
   {"random choice from (0, 1) (rc)", Dynamic@rc},
   {"list (l1)", Dynamic@l1},
   {"e", Dynamic@e},
   {"f", Dynamic@f}
   }, Alignment -> {{Right, Left}}],

 Initialization :> (
   update[] := Module[{c = 1},
     l1 = {};
     rc = RandomChoice[{a, b} -> {0, 1}];
     While[c <= d, AppendTo[l1, rc]; c++];
     e = ((Count[l1, _] - Count[l1, 0])/d)*100 // N;
     f = 100 - e;
     temp++;
     ];
   update[]
   )]