update readme

Author: hogan-tech

0227-basic-calculator-ii/0227-basic-calculator-ii.py

@@ -1,34 +1,38 @@
 # time complexity: O(n)
 # space complexity: O(n)
-class Solution:
+import math
+
 
+class Solution:
     def calculate(self, s: str) -> int:
-        if len(s) == 0:
-            return 0
+        num = 0
+        prevOperation = '+'
+        s += '+'
         stack = []
-        currNum = 0
-        operation = "+"
-        for i in range(len(s)):
-            c = s[i]
+        for c in s:
             if c.isdigit():
-                currNum = currNum * 10 + int(c)
-            if (not c.isdigit() and not s[i].isspace()) or i == len(s) - 1:
-                if operation == "-":
-                    stack.append(-currNum)
-                elif operation == "*":
-                    stack.append(stack.pop() * currNum)
-                elif operation == "+":
-                    stack.append(currNum)
-                else:
-                    tmp = stack.pop()
-                    if tmp // currNum < 0 and tmp % currNum != 0:
-                        stack.append(tmp // currNum + 1)
-                    else:
-                        stack.append(tmp // currNum)
-                operation = s[i]
-                currNum = 0
+                num = num*10 + int(c)
+            elif c == ' ':
+                pass
+            else:
+                if prevOperation == '+':
+                    stack.append(num)
+                elif prevOperation == '-':
+                    stack.append(-num)
+                elif prevOperation == '*':
+                    operant = stack.pop()
+                    stack.append((operant*num))
+                elif prevOperation == '/':
+                    operant = stack.pop()
+                    stack.append(math.trunc(operant/num))
+                num = 0
+                prevOperation = c
         return sum(stack)
 
 
 s = "3+2*2"
 print(Solution().calculate(s))
+s = " 3/2 "
+print(Solution().calculate(s))
+s = " 3+5 / 2 "
+print(Solution().calculate(s))

0227-basic-calculator-ii/README.md

@@ -81,19 +81,3 @@ By following these steps, users can easily navigate and utilize your LeetCode so
 
 We welcome contributions! If you have a solution to a problem that isn't already included, or if you have suggestions for improvements, please feel free to submit a pull request.
 
-
-<!---LeetCode Topics Start-->
-# LeetCode Topics
-## Math
-|  |
-| ------- |
-| [0227-basic-calculator-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0227-basic-calculator-ii) |
-## String
-|  |
-| ------- |
-| [0227-basic-calculator-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0227-basic-calculator-ii) |
-## Stack
-|  |
-| ------- |
-| [0227-basic-calculator-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0227-basic-calculator-ii) |
-<!---LeetCode Topics End-->

Python/0227-basic-calculator-ii.py

@@ -1,4 +1,4 @@
-<h2><a href="https://leetcode.com/problems/basic-calculator-ii/">227. Basic Calculator II</a></h2><h3>Medium</h3><hr><div><p>Given a string <code>s</code> which represents an expression, <em>evaluate this expression and return its value</em>.&nbsp;</p>
+<h2><a href="https://leetcode.com/problems/basic-calculator-ii">227. Basic Calculator II</a></h2><h3>Medium</h3><hr><p>Given a string <code>s</code> which represents an expression, <em>evaluate this expression and return its value</em>.&nbsp;</p>
 
 <p>The integer division should truncate toward zero.</p>
 
@@ -22,9 +22,8 @@
 
 <ul>
 	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
-	<li><code>s</code> consists of integers and operators <code>('+', '-', '*', '/')</code> separated by some number of spaces.</li>
+	<li><code>s</code> consists of integers and operators <code>(&#39;+&#39;, &#39;-&#39;, &#39;*&#39;, &#39;/&#39;)</code> separated by some number of spaces.</li>
 	<li><code>s</code> represents <strong>a valid expression</strong>.</li>
 	<li>All the integers in the expression are non-negative integers in the range <code>[0, 2<sup>31</sup> - 1]</code>.</li>
 	<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit integer</strong>.</li>
 </ul>
-</div>