From 3c90ce514e09e4bd9231020d85c3ccb0d0285ea8 Mon Sep 17 00:00:00 2001
From: tejaswipitchuka <67813989+tejaswipitchuka@users.noreply.github.com>
Date: Wed, 20 Oct 2021 21:59:49 +0530
Subject: [PATCH] Add files via upload

---
 python/postfixexpression_evaluation.py | 34 ++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 python/postfixexpression_evaluation.py

diff --git a/python/postfixexpression_evaluation.py b/python/postfixexpression_evaluation.py
new file mode 100644
index 0000000..5f209cc
--- /dev/null
+++ b/python/postfixexpression_evaluation.py
@@ -0,0 +1,34 @@
+'''
+Evaluate the value of an arithmetic expression in Reverse Polish Notation.
+Valid operators are +, -, *, /.Each operand may be an integer or another expression.
+
+'''
+
+class Solution:
+    def evaluateRPN(self, A):
+        stack=[]
+        top=-1
+        for i in A:
+            if(i!='+' and i!='-' and i!='*' and i!='/'):
+                stack.append(i)
+                top+=1
+                continue
+            else:
+                y=int(stack.pop())
+                top-=1
+                x=int(stack.pop())
+                top-=1
+                if(i=='+'):
+                    stack.append(x+y)
+                    top+=1
+                elif(i=='-'):
+                    stack.append(x-y)
+                    top+=1
+                elif(i=='*'):
+                    stack.append(x*y)
+                    top+=1
+                elif(i=='/'):
+                    stack.append(x//y)
+                    top+=1
+        return stack[top]
+                
\ No newline at end of file