It seems the test cases are modified after the contest. It no longer accepts random generated output.
The tester’s solution needs to be updated to pass the new test cases.
My submission(Copied from the one who tried random approach):
[CodeChef: Practical coding for everyone][1]
Sir I have one doubt what if by applying the 324 step on the further most,what if any random block becomes the further most(robot moves to further most block),then it is not necessary it will work by this approach.
really shocked to see that first soln. why do you put such question when you are not deterministic about solution. I even tried that random thing during contests but it failed system tests so should
i blame my luck or your question making abilities.
Edit : its still accepting that random soln.
I would be glad if can you help me know where i am getting this wrong
If do start bfs from point C and build a string array s[i][j].s[i][j] is the path from point C to point (i,j).After bfs just go to every (i,j) which is ‘.’ and reverse the string and replace ‘U’ with ‘D’ and ‘D’ with ‘U’ and R with L and L with R. Add all strings which contain path from (i,j) to C .
complexity is O(n^2).
if u manipulate string arrays while calculating bfs then complexity will be O(N).
Why does one need to find the string for the node farthest from the capital? Why can’t one start from any random node and follow rest of the procedure?
Can we select one non-prohibitted area which is near to the Capital city and then move to the capital city. This requires only two characters in the command but solution can be correct.
Please correct me if I am wrong because this way the solution can be very very easy.
I have a doubt regarding this question. It was mentioned that we can choose any non prohibited cell as the starting point. To reach C any of the U,D,L,R should be non prohibited. So, if I just start from any non prohibited cell that lies either U,or D,or L, or R of ‘C’ and then just take it to C using single instruction, why am I getting WA? Pardon me if I understood the question wronmg.
@karanaggarwal I started from the Capital and went to each and every city and then reversed the string and replaced L with R, U with D and vice-versa. For all my custom test cases the code worked fine. But still its not getting accepted (WA). If you could help me figure my mistake out, I would be grateful. Below is the link to my code.
Random note regarding bounds on total sum of path lengths - in order to have cell with distance 300 from capital, you need to have a cell with distance <=1, a cell with distance <=2, a cell with distance <=3 and so on - all of them will be on the path from our “bad cell” to the capital. With this observation you can safely decrease bound to something like 53k.
BTW, just curious - what’s the input file on which this algo produces longest possible string, and what’s the length of that string?
We had discovered it during the testing, we tried some test cases which can break some of the randomized solution. It was really hard to generate test cases for it. I would be interested if someone has a good test case to break such solutions.