sparse.h:	header file
p2_2.c:		main() for project 2 phase 2
****** 	These two files will be used for gradeing purpose. 
	Please read both carefully.

a.out:		
d234.txt:	output file when running 
    a.out ../DATA/s_in_2.txt ../DATA/s_in_3.txt ../DATA/s_in_4.txt d234.txt
		values for the positions: 1 1 3 3

    a.out s_in_1.txt a1.txt	(input: 1 7 1 8)
    a.out l_in_3.txt a7.txt 	(input: 13 14 83 29)
    a.out l_in_4.txt a8.txt 	(input: 81 5 3 387)
********************************************************************************
Sat May  2 18:39:22 EDT 2026
Q5. Can you post more sample output files?
A2. A couple more (a1.txt, a7.txt, and a8.txt) are posted. See above on how they
	are generated. Indeed, you can run the a.out on input files in ../DATA/
	directory to generate as many sample output files as you want. 


Sat May  2 18:29:19 EDT 2026
Q4. Will there be any test cases on the large input files?
A4. Yes. There will be. Also for large graph, the path between two entries may
	not be uniques. So your answer does not need to be exactly the same as
	that in the sample output file.


Sat May  2 10:43:55 EDT 2026
Q3. Do I have to use the "new structure" described in the slides for project 2?
A3. You do not have to. But as we have discussed in the class, using such structure
	can (significantly) help in implementing (some) functions for phase 2 of the 
	project. 
    You can also define your own structures. If you do that, they have to be 
	defined and used in your sparse_2.c (remember that you cannot change p2_2.c
	and sparse.h). 


Sat May  2 10:33:27 EDT 2026
Q2. How to run the a.out you posted here?
A2. 	copy a.out to your own directory for project 2
	assume that the input files are in the same directory
    a.out s_in_2.txt s_in_3.txt s_in_4.txt d234.txt
	if the input files are in another directory, say in subdirectory DATA/
	   (and the subdirectory DATA/ is in the same difectory of a.out), then
    a.out DATA/s_in_2.txt DATA/s_in_3.txt DATA/s_in_4.txt d234.txt


Sat May  2 08:37:59 EDT 2026
Q1. in d234.txt, the transpose matrix is printed out in the order as the original
	matrix, but the reverse matrix is printed out in the normal matrix order
	(by each row and by the column in the same row). Is there a reason for 
	this? Can I print out both in the matrix oder? 
A1.
   Good catch! It happend that way because in our sample code, the next pointer
	for each matrix ENTRY was not used in building transpose, but was used
	in building reverse. Both matrices were printed out by show_list(), which
	uses the next pointer, so they appear in different order. 
   I have moved the old output to d234.bak and generate the new d234.txt output
	where both matrices are printed out in the "matrix order".
   Indeed, we should have required the matrix to be printed out in "matrix order".
	But for the grading purpose, it is ok if you print it out in a different
	order as long as the matrix entry information (val, row, col) is correct.