Programming :: Algorithm For Binary Frequency Search?

I've got a bit of an obscure question for you to test your brains a wee bit. I'm trying to implement a search program to find areas of high density in a binary string.

E.g.

Code:

[0001001010
0001110001
0000001000
1001000010
0101100100]

Where density is the number of 1's / number of digits with a maximum number of digits being the current number in a buffer (in this example 50). So for the example the density for the whole buffer is 15/50. But the density of Buffer[14..20]=[1110001]=4/7. So if looking for areas of density = 1/3 it would find the longest sequences of density over 1/3.So in the example. Buffer[4..9]=[100101]=3/6=1/2 which is above 1/3 but it is within the Buffer[4..48]=[100101000011100010000001000100100001001011001]=15/45=1/3