A stack is an ordered collection of items into which new items may be inserted and from which items can be deleted at one end,called top of stack.It is First In Last Out(FILO) type of data structure.
Stack can be thought as pile of plates one on other.One which is put first stay at last or bottom of pile and one that is pile last is always on top.Also to take out a plate form it one which is on top is remove first and other later.That's why it is called FILO.
Push is the process of adding data on top of stack.
Pop is the process of removing data from top of stack.
a)Top of stack varying method:
1)Declare and initialize necessary variables e.g. top=-1 , Max_Size.
2)For Push operation-
IF top=Max_Size-1
print" Stack is Full "
ELSE
top=top+1
READ items from user
Stack[top]=item
3)For next Push operation go to step 2
4)For Pop operation-
IF top=-1
print" Stack is Empty "
ELSE
item=Stack[top]
top=top-1
Display item
5)For next Pop operation goto step 4
6)Stop]
b)Top of stack fixed method:
1)Declare and initialize necessary variables
e.g. Bos=0,Max_Size etc.
2) For Push operation-
IF BOS=Max_Size
print"Stack Overflow!"
ELSE
insert new element by making vaccant space at stack[0] location
3)For next Push operation goto step2
4)For Pop operation -
IF BOS=0
print "Stack is Empty!"
ELSE
remove item from stack [0]
BOS--
refill empty space by lowering each step by 1
5)For next Pop operation goto step4
6)Stop
Stack can be thought as pile of plates one on other.One which is put first stay at last or bottom of pile and one that is pile last is always on top.Also to take out a plate form it one which is on top is remove first and other later.That's why it is called FILO.
Pop is the process of removing data from top of stack.
Stack Algorithms:
There are basically two methods implement stack:- a)Top of stack varying method:
1)Declare and initialize necessary variables e.g. top=-1 , Max_Size.
2)For Push operation-
IF top=Max_Size-1
print" Stack is Full "
ELSE
top=top+1
READ items from user
Stack[top]=item
3)For next Push operation go to step 2
4)For Pop operation-
IF top=-1
print" Stack is Empty "
ELSE
item=Stack[top]
top=top-1
Display item
5)For next Pop operation goto step 4
6)Stop]
b)Top of stack fixed method:
1)Declare and initialize necessary variables
e.g. Bos=0,Max_Size etc.
2) For Push operation-
IF BOS=Max_Size
print"Stack Overflow!"
ELSE
insert new element by making vaccant space at stack[0] location
3)For next Push operation goto step2
4)For Pop operation -
IF BOS=0
print "Stack is Empty!"
ELSE
remove item from stack [0]
BOS--
refill empty space by lowering each step by 1
5)For next Pop operation goto step4
6)Stop
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