Question

Search(T,k)
x<- root[T]
while x != NULL and k != key[x] 
do 
  if k<key[x]
    then x <- left[x]
  else x <- right[x]
    return x

I just started with algorithms and I often see “<-” this and key[x] terminology can someone tell me what is key is it an array ? x was getting the root value and then it is used as an index ? I fail to understand this. Please explain.

Answer 1

It’s pseudocode (not a real language).

In this case <- means ‘is assigned’ and can be thought of as doing what = does in modern languages. key[x] is shorthand for the key property of structure/object x (this doesn’t mean it’s a member of the x class necessarily, it could be retrieved from a data structure such as a map. The actual implementation is left up to the algorithm implementer.

So the above algorithm could be written in C as:

Node* Search(Tree* T, Key k)
{
    Node* x = T->Root();
    while ((x != NULL) && (k != x->Key())
    {
        if (k < x->Key())
            x = x->Left();
        else
            x = x->Right();
    }

    return x;
}