D. J.:

- Added the leetcode problem and solution for 150 Evaluate Reverse Polish Notation

Author: nobodyPerfecZ

README.md

@@ -40,6 +40,7 @@ This repository contains awesome LeetCode problems and solutions written in Pyth
 - [122 Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/description/)
 - [125 Valid Palindrome](https://leetcode.com/problems/valid-palindrome/description/)
 - [128 Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/description/)
+- [150 Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/description/)
 - [155 Min Stack](https://leetcode.com/problems/min-stack/description/)
 - [169 Majority Element](https://leetcode.com/problems/majority-element/description/)
 - [189 Rotate Array](https://leetcode.com/problems/rotate-array/description/)

awesome_python_leetcode/_150_evaluate_reverse_polish_notation.py

@@ -0,0 +1,39 @@
+from typing import List
+
+
+class Solution:
+    def evalRPN(self, tokens: List[str]) -> int:
+        """
+        You are given an array of strings tokens that represents an arithmetic expression in a Reverse Polish Notation.
+
+        Evaluate the expression. Return an integer that represents the value of the expression.
+
+        Note that:
+        - The valid operators are '+', '-', '*', and '/'.
+        - Each operand may be an integer or another expression.
+        - The division between two integers always truncates toward zero.
+        - There will not be any division by zero.
+        - The input represents a valid arithmetic expression in a reverse polish notation.
+        - The answer and all the intermediate calculations can be represented in a 32-bit integer.
+        """
+        stack = []
+        for t in tokens:
+            if t == "+":
+                second = stack.pop()
+                first = stack.pop()
+                stack.append(int(first + second))
+            elif t == "*":
+                second = stack.pop()
+                first = stack.pop()
+                stack.append(int(first * second))
+            elif t == "-":
+                second = stack.pop()
+                first = stack.pop()
+                stack.append(int(first - second))
+            elif t == "/":
+                second = stack.pop()
+                first = stack.pop()
+                stack.append(int(first / second))
+            else:
+                stack.append(int(t))
+        return stack[0]

tests/test_150_evaluate_reverse_polish_notation.py

@@ -0,0 +1,18 @@
+from typing import List
+
+import pytest
+
+from awesome_python_leetcode._150_evaluate_reverse_polish_notation import Solution
+
+
+@pytest.mark.parametrize(
+    argnames=["tokens", "expected"],
+    argvalues=[
+        (["2", "1", "+", "3", "*"], 9),
+        (["4", "13", "5", "/", "+"], 6),
+        (["10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"], 22),
+    ],
+)
+def test_func(tokens: List[str], expected: int):
+    value = Solution().evalRPN(tokens)
+    assert value == expected