From 02dddde371b72ef4da4e86d5290c0aa40cf09667 Mon Sep 17 00:00:00 2001
From: Nimit Arora <nimit17arora@gmail.com>
Date: Thu, 5 Oct 2017 22:24:00 +0530
Subject: [PATCH] Postfix Evaluation

---
 Misc/PostfixEvaluation.java | 70 +++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Misc/PostfixEvaluation.java

diff --git a/Misc/PostfixEvaluation.java b/Misc/PostfixEvaluation.java
new file mode 100644
index 000000000000..ab70a4f2a54e
--- /dev/null
+++ b/Misc/PostfixEvaluation.java
@@ -0,0 +1,70 @@
+import java.util.Scanner;
+import java.util.Stack;
+
+/*
+This Program will evaluate the value of given Postfix Expression
+ */
+
+public class PostfixEvaluation {
+    public static void main(String[] args) {
+        // Inserting Postfix Expression
+        System.out.println("Enter Postfix Expression");
+        Scanner s=new Scanner(System.in);
+        String exp=s.next();
+        int answer=PostEval(exp);
+        System.out.println("The Value of expression is : "+answer);
+    }
+
+    //Function to Evaluate Postfix Expression
+
+    private static int PostEval(String exp) {
+        Stack<Integer> helperStack=new Stack<>();
+        int i=0;
+        while(i<exp.length())
+        {
+            if(exp.charAt(i)=='*')
+            {
+               Integer  A=helperStack.pop();
+               Integer  B=helperStack.pop();
+               Integer  C=B*A;
+               helperStack.push(C);
+            }
+            else if(exp.charAt(i)=='/')
+            {
+                Integer  A=helperStack.pop();
+                Integer  B=helperStack.pop();
+                Integer  C=B/A;
+                helperStack.push(C);
+            }
+            else if(exp.charAt(i)=='^')
+            {
+                Integer  A=helperStack.pop();
+                Integer  B=helperStack.pop();
+                Integer  C=(int) Math.pow((double) B,(double)A);
+                helperStack.push(C);
+            }
+            else if(exp.charAt(i)=='+')
+            {
+                Integer  A=helperStack.pop();
+                Integer  B=helperStack.pop();
+                Integer  C=B+A;
+                helperStack.push(C);
+            }
+            else if(exp.charAt(i)=='-')
+            {
+                Integer  A=helperStack.pop();
+                Integer  B=helperStack.pop();
+                Integer  C=B-A;
+                helperStack.push(C);
+            }
+            else
+            {
+                helperStack.push(Integer.parseInt(""+exp.charAt(i)));
+            }
+            i++;
+        }
+        int ans=helperStack.pop();
+        return ans;
+
+    }
+}