[Community Puzzle] Tree Paths

Puzzles
#22

One week i am trying but nothing , then help me please

#23

My recursive method not working

#24

Are you getting a wrong answer, or is your code not getting that far?

#25

This may help:

#26

I pass the two first test but the rest none

I want to use the recursive function inside the for loops but did not work

#27

It’s hard to give proper help, as I don’t know what did you try and where are you stuck. Do you need help in finding the algorithm to solve it, OR you know it already but don’t know how to write proper code for it?

As a hint for the first case: while you can go with complete tree traversals and/or recursion, this puzzle can be solved without them.
For example, besides the input/output handling, my code is basicly a simple while loop.

Spoiler alert: …and the loop goes from the target node to the root, and not vice versa.

#28

I don’t know the algorithm , in the first tume i am looking for a recursion but look like complicate.

I you explain me the algorithm i will find a way to write the code properly.

Thanks you !

#29

When storing all the input in some data structure of your choice, make sure that you can easily lookup any node’s left child, right child, and also it’s parent.
Then, you can make a loop, starting from the target node, always moving towards the parent, while you reach the root. When moving up, you can decide whether the node where you came from was the left or the right child of the parent. By storing this info, by the time you reached the root, you have the full puzzle answer, but in reverse order.

PS: I see you solved 3 puzzles on CG. There are plenty of puzzles, some are much easier than this one. It is not a problem to put this aside, solve some others and to come back to this only later.

#30

Thank you so much for the advice . Obviously i solved 3 puzzles in CG i am just starting.

If i understand , the first thing is to store the tree ( all node value ) in a data structure like an array. After that , searched the target value , once found go back to the root.

My question is how to remember the direction a node come from.

#31

Let’s assume you came from node “x” and moved to its parent, node “y”, (y = parent[x]). You can check whether if (left[y] == x) or elseif (right[y] == x).

#32

Thank you very much TBali , I really appreciate you it , but i think i have to give i tried my best but nothing .

THANK YOU FOR YOUR SUPPORT .

#34

i tried this in bash. creating an actual tree on the file system. using the command line tool “find” to traverse the tree and find the target for me.
all tests work. all validators work except validator 4.
the test cases given in this thread all work.
any help?

#35

Validator 4 is the same as test case 4 except for the second input (i.e. index of the target node). That means you may debug your code by varying that input to see for what input value your code gives a wrong output.

#36

thank you for the tip. i tried all 9 possible values in the tree. all were working correctly. i even tried replacing some numbers with symbols like “-”. even then it still worked correctly. i fear the problem is elsewhere.

#37

What are your outputs for each of the 9 possible values?

#38

thank you for double checking. i very well could have made a concentration error.

for this input

9
X
4
1 2 3
2 4 5
3 9 8
8 6 7

output for all X

X Output
1 Root
2 Left
3 Right
4 Left Left
5 Left Right
6 Right Right Left
7 Right Right Right
8 Right Right
9 Right Left

i did this table twice to double check against copy paste errors.

1 Like
#39

Ah ok, yes, all outputs are correct. You should have passed validator 4 then. Yup, probably a concatenation error.

#40

just to clarify: my code still does not pass validator 4.

my remark about my possible concentration error was referring to the laborious task of manually entering the number and expected output. i very well could have made a mistake there. but now i have double (triple) checked with confirmation from a third party (thank you 5DN1L) that my code is indeed returning the correct result. still not passing validator 4.

#41

That is weird. Try testing it within CodinGame as a custom test case and see what error you get.

#42

i did test it within codingame using the custom test case feature. that was where i did the laborious manual task.