计算逆波兰表达式

Azureki · Oct 28, 2018 · f629be7 · f629be7
1 parent c6debea
commit f629be7
Showing 1 changed file with 30 additions and 0 deletions.
diff --git a/lc150. Evaluate Reverse Polish Notation.py b/lc150. Evaluate Reverse Polish Notation.py
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+class Solution:
+    def evalRPN(self, tokens):
+        """
+        :type tokens: List[str]
+        :rtype: int
+        """
+        operators = {'+', '-', '*', '/'}
+        oprd = []
+
+        for tk in tokens:
+            if tk in operators:
+                b = oprd.pop()
+                a = oprd.pop()
+                if tk == '+':
+                    c = a + b
+                elif tk == '-':
+                    c = a - b
+                elif tk == '*':
+                    c = a * b
+                else:
+                    c = int(a / b)
+                oprd.append(c)
+            else:
+                oprd.append(int(tk))
+        return oprd[0]
+
+
+tokens = ["10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"]
+s = Solution()
+print(s.evalRPN(tokens))