Hey,
My code was passing all the test cases but was failing a tunnel validator too.
when you check the animation for tunnel validator I could see that it was not printing the data for the lowest level points.
I assumed that,like in all other puzzles, if the height is H then the lowest point will be either 0 either H-1. But here it is actually H as it turned out.
so if youre using a for(;;){} loop, then consider checking you actually cover all the area 
I usually code in C++. This kinda looks like python, but python doesn’t do i++. I think I can still read the code even though I’m not sure what language this is.
I traced through searchNextD. the First return was c.x =1 c.y =0;
My second time going through:
while (1 <= 2 or grid[0,1] is ‘0’) //go into because 1<=2 also [0,1] is ‘0’ either
if (1 == 2-1) //break out of while loop
if (grid[0,1] != ‘0’) //grid[0,1] does == ‘0’ so we won’t change x or y to -1
return c.x = 1 c.y = 0
So we started with x=0 y=0
After first pass x=1 y=0
After second pass x=1 y=0
After Third pass x=1 y=0
…
Your X and Y will never update because X won’t increment.
I’m not a superstar at coding, do you think I figured it out or did I get it wrong?
True. I struggled for 15 minutes until I realised I’ve switched x and y when I added the nodes in my vector. Modified it and everything went green.
What in the world is ‘invalid node’? What makes a node invalid?
Please share a link to your replay (look for the button near the lower right corner of the viewer), which may help others answer your questions.