As for coding Pascal's triangle? It took me <30 seconds to Google it and find code I could copy/paste.
To be honest, seeing about 200 lines that looked like this:
typedef struct Abc {
Abc *n;
Abc *p;
void *d;
} Abc;
Abc *foo(Abc *p, void *x)
{
Abc *n;
n = malloc(sizeof(Abc*));
n->p = NULL;
n->n = p;
n->d = x;
p->p = n;
return p;
}
Sorting it out was a bit of a challenge. I think the specific question that I was looking at deobfuscated into reading words and definitions in from the command line and maintaining them in a sorted list, then looking up the words and printing their definitions.
And I agree, it was a great interview question. I even had the ability to sit in front of the computer and test my fixes to make sure it worked.
1. You need to malloc 3 words, and you're only allocating one (you want sizeof(Abc)) 2. Abc in the struct will not resolve (change to struct _Abc and the struct name to _Abc) 3. You should cast the result of malloc/check for failure 4. This is bad memory management practice, I think.
2) No, 'struct Foo' is in a different namespace from the typedef'ed name. 'typedef struct Foo Foo' is perfectly valid.
3) Yes, absolutely.
4) Not sure what you mean.
Here's a hint: You'll likely miss one of them unless you realize what the algorithm is trying to do. It's an algorithmic error. The other one is findable from looking at the code without context, but the correct fix isn't entirely obvious without realizing the way the code works.
Pretty good, though :)
I think function foo is supposed to insert a new node (n) into the list before node p, but it's not done properly (while n points to p and p points to n, n does not point back to the item before p).
That should be enough for you to figure the last 2 errors, in any case.
n->p = p->p
I don't see the last one - unless foo should be returning n?
prepend(NULL, &something);
if (p != NULL)
p->p = n;
I don't think I'd expect everyone to get every bug without a little bit of prodding in the right direction. Being able to step through the code and show what it's doing to the data structures would be a first step that would make me happy. Recognizing that the data structure looked like it's a linked list, and finding and and fixing a couple of the bugs, and I'd be very happy.
Unfortunately C++ requires the cast.