Create minimum-costs-using-the-train-line.py

Author: kamyu104

Python/minimum-costs-using-the-train-line.py

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+# Time:  O(n)
+# Space: O(1)
+
+import itertools
+
+
+# dp
+class Solution(object):
+    def minimumCosts(self, regular, express, expressCost):
+        """
+        :type regular: List[int]
+        :type express: List[int]
+        :type expressCost: int
+        :rtype: List[int]
+        """
+        result = []
+        dp = [0, expressCost]  # dp[0]: min cost of regular route to curr stop, dp[1]: min cost of express route to curr stop
+        for r, e in itertools.izip(regular, express):
+            dp = [min(dp[0]+r, dp[1]+e), min(dp[0]+(r+expressCost), dp[1]+e)]
+            result.append(min(dp[0], dp[1]))
+        return result