Question

please answer these two questions properly about Stack data structure

Q(1) What are their respective logical and physical / storage structures .Q(2) At least one application example combining data structure and algorithm should be given.

Answer 1

Q(1). Logical storage structures:

Logical data structure or a logical storage sructure are data structures that can be built using physical storage structure like array and linkedlist. Logical storage structures denotes content, context of the data.

For example: Qeue, stack, tree , hash table etc.

Physical storage structures:

Physical storage structures or physical data structures are built based on physical aspects of the data .Physical storage structure shows the format and memory location of the data stored in a memory.

for example: Array, Linkedlist.

Q(2).Application example of a stack and its algorithm:

Stacks are most commonly used in evaluation of postfix,infix and prefix of an expression.

lets consider evaluating postfix of an expression using stack as an example

-To evaluate postfix of an expression, the expression us scanned from left to right and if an operand is found it is pushed into the stack.

-If the element is an operator two elements are popped out of stack.

-Repeat it till the end of the expression.

ALGORITHM:

1. add ) to postfix expression.
2. scan from left to right until ) is found.
3. if an operand found push it into the stack.
4. if an operator is found pop two elements.
5. a==>top of the stack
6. b==>second element of the stack
7. evaluate b to a with respect to operator
8. push b operator a to the stack
9. result=pop
10. END