adding cs235

cs235/lab04/shunting/__init__.py

@@ -0,0 +1,23 @@
+from collections import deque
+
+
+op_prec = {
+    '*': 3,
+    '/': 3,
+    '%': 3,
+    '+': 2,
+    '-': 2,
+}
+
+
+def shunt(tokens):
+    tokens = deque(tokens)
+    output = deque()
+    operators = deque()
+    while tokens:
+        token = tokens.pop()
+        if token.isdigit():
+            output.append(token)
+        elif token in op_prec:
+            operators.append(token)
+    return output, operators