FilesExpand file tree

 master

/

StackPostfixNotation.java

Copy path

BlameMore file actions

BlameMore file actions

Latest commit

 

History

History

History

40 lines (34 loc) · 1.28 KB

 master

/

StackPostfixNotation.java

Top

File metadata and controls

• Code
• Blame

40 lines (34 loc) · 1.28 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

package Others;

import java.util.*;

public class StackPostfixNotation {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

String post = scanner.nextLine(); // Takes input with spaces in between eg. "1 21 +"

System.out.println(postfixEvaluate(post));

}

// Evaluates the given postfix expression string and returns the result.

public static int postfixEvaluate(String exp) {

Stack<Integer> s = new Stack<Integer>();

Scanner tokens = new Scanner(exp);

while (tokens.hasNext()) {

if (tokens.hasNextInt()) {

s.push(tokens.nextInt()); // If int then push to stack

} else { // else pop top two values and perform the operation

int num2 = s.pop();

int num1 = s.pop();

String op = tokens.next();

if (op.equals("+")) {

s.push(num1 + num2);

} else if (op.equals("-")) {

s.push(num1 - num2);

} else if (op.equals("*")) {

s.push(num1 * num2);

} else {

s.push(num1 / num2);

}

// "+", "-", "*", "/"

}

}

return s.pop();

}

}