Question 150

Author: shubhamkumar27

150. Evaluate Reverse Polish Notation.py

@@ -31,3 +31,28 @@
 = 22
 '''
 
+class Solution:
+    def evalRPN(self, arr: List[str]) -> int:
+        stack = []
+        for i in range(len(arr)):
+            if arr[i]=='+':
+                num1 = stack.pop()
+                num2 = stack.pop()
+                stack.append(num2+num1)
+            elif arr[i]=='-':
+                num1 = stack.pop()
+                num2 = stack.pop()
+                stack.append(num2-num1)
+            elif arr[i]=='*':
+                num1 = stack.pop()
+                num2 = stack.pop()
+                stack.append(num2*num1)
+            elif arr[i]=='/':
+                num1 = stack.pop()
+                num2 = stack.pop()
+                stack.append(int(num2/num1))
+            else:
+                stack.append(int(arr[i]))
+            # print(stack)
+        return stack[0]
+