Thread: Memory in lists

So basically I'm struggling with question 5 in this assignment,http://www.student.cs.uwaterloo.ca/~...ssignments/a5/We are basically given functions that act like Scheme list functions and in question 5 I am supposed to create a function called iappend, which appends two lists. This is my code and it seems to work.

Code:

ilist iappend(ilist il1, ilist il2) {
    ilist acc = iempty();
    ilist acc1 = iempty();
    ilist a;
    while (!iempty_huh(il1)) {
        acc1 = icons(ifirst(il1), acc1);
        il1 = irest(il1);
    }
    while (!iempty_huh(il2)) {
        acc1 = icons(ifirst(il2), acc1);
        il2 = irest(il2);
    }
    a = acc1;
    while (!iempty_huh(acc1)) {
        acc = icons(ifirst(acc1), acc);
        acc1 = irest(acc1);
    }
    idelete(a);
    return acc;
}

but they want this code to be more efficient, can somewone help me code, so i won't make a temporary list ? I need to code it in such a way that i won't use idelete .... any suggestions would help , Thanks !

Use exactly the same algorithm you'd use with a string of beads or popcorn, at your kitchen table. Simple is fast.

Sorry, im new with pointer's, how exactly would i find the end of the first list and point it to the second? also im suppose to "build-a-newlist" so i need to somehow put the inputs in a variable such as my acc

Originally Posted by Adak

Use exactly the same algorithm you'd use with a string of beads or popcorn, at your kitchen table. Simple is fast.

i don't quite understand your analogy ? lol