Question

Java please

5. Using the following postfix expressions, use a class) to stack (or the method we used in (12 pts-6 eaeh) solve them producing a final result. (a) 69 5 725 7*+-18 25 5,2025 20%+ (b) 2 3+ 5-6 78+ 45 5 % 12 3/++ -

Answer 1

§子 25 5 兵nal result 3 5 35 6161 45 20 끄35

8 5 61 5- 5 マ+3 56 , , e62- Fin ves 12 -66 -66 62 0-66 12 45 /.5 -66

code:

import java.util.Stack;

public class Test

{

public static boolean isNumeric(String str)  

{  

try{

double d = Double.parseDouble(str);  

}  

catch(NumberFormatException nfe){  

return false;  

}  

return true;  

}

public static int evaluatePf(String expression)

{

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

String[] ops=expression.split(" ");

for(int i=0;i<ops.length;i++)

{

String c=ops[i];

// push to the stack when it is a number,

if(Test.isNumeric(c))

stack.push(Integer.parseInt(c));

// when it is an operator, pop the top two elements and apply the operator and push the result again

else

{

int v1 = stack.pop();

int v2 = stack.pop();

switch(c)

{

case "+":

stack.push(v2+v1);

break;

case "-":

stack.push(v2- v1);

break;

case "/":

stack.push(v2/v1);

break;

case "*":

stack.push(v2*v1);

break;

case "%":

stack.push(v2%v1);

break;

}

}

}

return stack.pop();

}

public static void main(String[] args)

{

String expression="69 5 7 25 7 * + - 18 25 5 / 20 25 20 % + * + + +";

System.out.println(evaluatePf(expression));

}

}