cartalk1, why using i=i+1-2*count?

[Naolador]

I just don't understand why we use "i = i + 1 - 2*count" to reset the pointer in line 31 if two nearby characters doesn't match. I replaced the line with "i = i + 1" and got the same result.

[jerryu]

I am also curious, so I added some debugging code to output

• the partial string yet to check at the beginning of the iteration.
• the values of i and count, at beginning and the end of each iteration

The i=i+1 proposed by Naolador seems to have the desirable/expected flow.

Allowing overlapped counting might require walking the pointer back, depending on the flow.
To illustrate, I made up a word, 'booookmaker'.
Both solutions don't allow overlapping, whereas the second 'o' forms one double with 'o' before and another double with 'o' after.

 reset	booookmaker	0	0	1	0		 reset	booookmaker	0	0	1	0
 double	 ooookmaker	1	0	3	1		 double	 ooookmaker	1	0	3	1
 double	   ookmaker	3	1	5	2		 double	   ookmaker	3	1	5	2
 reset	     kmaker	5	2	2	0	      |	 reset	     kmaker	5	2	6	0
 double	  oookmaker	2	0	4	1	      <
 reset	    okmaker	4	1	3	0	      <
 double	   ookmaker	3	0	5	1	      <
 reset	     kmaker	5	1	4	0	      <
 reset	    okmaker	4	0	5	0	      <
 reset	     kmaker	5	0	6	0	      <
 reset	      maker	6	0	7	0		 reset	      maker	6	0	7	0
 reset	       aker	7	0	8	0		 reset	       aker	7	0	8	0
 reset	        ker	8	0	9	0		 reset	        ker	8	0	9	0
 reset	         er	9	0	10	0		 reset	         er	9	0	10	0