Question

Write a function using c that combines two lists by alternatingly taking elements from the two lists that are passed to it. e.g. [a,b,c], [1,2,3] → [a,1,b,2,c,3].

Answer 1

//Function to combines two lists alternatively

struct Node *combinelist(struct Node *a,struct Node *b)
{
if(!a)
return b;
  
if(!b)
return a;

struct Node *head=a,*res=a,*prev=NULL;
while(a && b)
{
struct Node *t=a->next;
   struct Node *q=b->next;
res->next=b;
res=res->next;
res->next=t;
prev=res;
res=res->next;
a=t;
b=q;
}
if(a)
prev->next=a;
else if(b)
prev->next=b;

return head;
}

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