stack & queue

Stack & Queue

Winter-Camp-2011CSIE.NTNU

N.S.Lin@csie.ntnu@Taiwan

CC – 非商業性 – 相同方式

Stack

• 一種串列式資料結構• LIFO (Last In First Out)

Stack Sample

Make a Stack

0 1 2 3 4 5 6 7-1

if (pointer < 0) null.

if (pointer == SIZE) full.

#define SIZE 8int my_stack[SIZE];int pointer = -1

Queue

• 一種串列式資料結構• FIFO(First In First Out)

Queue Sample

Make a Queue

0 1 2 3 4 5 6 7

if (front == rear) null.

if (rear == SIZE) full.

Circular Queue

Stack Applications

• LISP functions

• Infix to Postfix

LISP Functions

LISP Functions

( 　　 ( ( 　　 ) ( 　　 ) ) )oddp - 5 2+ * 2 3

LISP Functions

( 　　 ( ( 　　 ) ( 　　 ) ) ) - 將左括號放入 stack ， 看到右括號就從 stack 拿出一個左括號

(

(

((

Infix to Postfix

• Infix : (1 + 2) * 3 + 4• Postfix : 1 2 + 3 * 4 +

Infix to Postfix

• Use a Stack• Output the numbers• Push operators into the stack– If there are operators having higher(or equal)

precedence, pop them.– When read ) , pop all operators until pop a ( .

Infix to Postfix

• Operator Precedence

– Outside : ( > * = / > + = -– Inside : * = / > + = - > (

Infix to Postfix

• ( 1 + 2 ) * 3 / 4

(*

+

/

1 2 + 3 * 4 /

Queue Applications

• BFS

Test Yourself

• 673 - Parentheses Balance• 271 - Simply Syntax• 727 - Equation

Test YourselfPractice:Use a Circular Queue

Sample Input:100200-1420-1-110-10

Sample Output:100200420