How do you use “is in list” with a list of list?

[Ludovik]

Hello,
I created a list of list associating a number with an object.
I want to check that there are no duplicate numbers with the "is in list?" Block.
Can you explain to me how to do it.
Thank you!

App inventor|690x311

[nishyanthkumar]

@Ludovik

I want to check that there are no duplicate numbers with the "is in list?" Block.

Sorry, I didn't see that. You won't have to use a Dictionary for that, as I stated in my above post...
Here's how I would do it (this is pretty Java-esque):

[dora_paz]

Another approach is like this

[Ludovik]

Thank you very much, I try that.

[nishyanthkumar]

I'd recommend using @dora_paz's code, since mine is pretty tacky and ineffective.

[Ludovik]

Thanks dora_paz, it works perfectly.