What is memory allocation? Explain the first fit and best fit algorithms for storage
allocation with suitable examples. 


Memory Allocation : It is the technique of allocating memory storage to
program in order that the program can be run.
First fit algorithm: The question asked for examples not algorithms the first
fit algorithm may be explained.
Suppose the memory allocation is as follows: suppose
indicates allocated block & denotes a free block.
The size of the free blocks are indicated. Suppose the current
requirement is 8K. Then the first fit algorithm will allocate it from
the block of 20K.
The advantage ; it is part disadvantage : fragmentation.
P=freeblock
aloc= null
q=null;
while (p!=null && size (p) < n )
{
Q=p;
p=next(P)
}/* end while */
if (p!=null){/* there is block large enough*/
s=size(p);
alloc=p+s-n; /* alloc contain the address of the designed
block*/
if(s==n)
/* remove the block from the free list*/
if (q==null)
freeblock=next(p);
else
next(q)=next(p);
else
/* adjust the size of tile remaining free block*/
size(p)=s-n;
}/* end if*/
The Best fit algorithm : The best fit method obtains the smallest free block
whose size is greater than or equal to n. An algorithm to obtain such a block
by traversing the entire free list follows. We assume that the memsize is the
total no. of words in memory.
The Best fit algorithm allocates the memory from the block that fits the
requirement best i.e. the block that has size greater than the requirement, but
no other block of lesser size can meet the requirement. Thus for the above
problem the allocation will be made from block of size 10 K. Advantage :
fragmentation is reduced
Disadvantage : more time.