# Solved! Leetcode 2361: Minimum Costs Using the Train Line

A train line going through a city has two routes, the regular route and the express route. Both routes go through the same n + 1 stops labeled from 0 to n. Initially, you start on the regular route at stop 0.

You are given two 1-indexed integer arrays regular and express, both of length n. regular[i] describes the cost it takes to go from stop i – 1 to stop i using the regular route, and express[i] describes the cost it takes to go from stop i – 1 to stop i using the express route.

You are also given an integer expressCost which represents the cost to transfer from the regular route to the express route.

Note:

• There is no cost to transfer from the express route back to the regular route.
• You pay expressCost every time you transfer from the regular route to the express route.
• There is no extra cost to stay on the express route.
• a stop can be counted as reached from either route.

Return a 1-indexed array costs of length n, where costs[i] is the minimum cost to reach stop i from stop 0.

Input: regular = [1,6,9,5], express = [5,2,3,10], expressCost = 8
Output: [1,7,14,19]
Explanation:

• Take the regular route from stop 0 to stop 1, costing 1.
• Take the express route from stop 1 to stop 2, costing 8 + 2 = 10.
• Take the express route from stop 2 to stop 3, costing 3.
• Take the regular route from stop 3 to stop 4, costing 5.
The total cost is 1 + 10 + 3 + 5 = 19.
Note that a different route could be taken to reach the other stops with minimum cost.

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