Merge 2 sorted list ::linked list::RunError

https://hack.codingblocks.com/contests/c/424/117

https://ide.codingblocks.com/#/s/15026

https://ide.codingblocks.com/#/s/15564
tail=tail->next

didn’t get it.
I did

tail->next=ptr;
tail=ptr // same as tail=tail->next;

my code gives right output for test case as well.

no thats not the error u are doing arri1[n] and same for arr2 that will not pass some of your cases give sizes to them or allocate dynamically.
Also in the question u have take 2 link list not array so try using that.