algo_021

Problem Statement

Problem Statement

Write an algorithm to insert a node at the beginning of a double linked list.

Algorithm

procedure insert_begin(dl, val)
begin
    ptr ← getNode();
    info(ptr) ← val;
    prev(ptr) ← NULL;
    next(ptr) ← NULL;
    if(dl = NULL)
        dl ← ptr;
    else
        next(ptr) ← dl;
        prev(dl) ← ptr;
        dl ← ptr;
    endif
    return(dl);
end procedure