In 212895b5 - Ex.1 output - red diagonal line in the upper-left corner ends too early

[petkish]

[GaussianMongrel]

Can you please share the other examples for this puzzle in your comment above, so readers and have more context.

[petkish]

Sure,

[MischaMegens2]

"Two gray pixels straddling the red line block it", what's wrong with that?

[petkish]

Every other way of blocking is shown at least a couple of times, e.g. blocking by gray on the way is done 4 times.
Block by a straddling line is not en error per se, but very probably not what was intended by the author of this task.

[MischaMegens2]

Every other way of blocking is shown at least a couple of times, e.g. blocking by gray on the way is done 4 times. Block by a straddling line is not en error per se, but very probably not what was intended by the author of this task.

Sounds convincing to me. It would make the puzzle easier to understand, for sure.

[kungfu-eric]

The pattern is if there is two grey blocks straddling the yellow or red line in the direction of travel it stops the strand.

[MischaMegens2]

The pattern is if there is two grey blocks straddling the yellow or red line in the direction of travel it stops the strand.

Where do you get that, that any grey blocks straddling a yellow line in the direction of travel would stop the strand? Do you see that demonstrated in any of the examples?