[LeetCode] 983. Minimum Cost For Tickets (Medium/Python)

Minimum Cost For Tickets - LeetCode

Above is the link to the problem.

 

Problem

You have planned some train traveling one year in advance.

The days of the year in which you will travel are given as an integer array "days".

Each day is an integer from 1 to 365.

Train tickets are sold in three different ways:

• a 1-day pass is sold for "costs[0]" dollars,
• a 7-day pass is sold for "costs[1]" dollars, and
• a 30-day pass is sold for "costs[2]" dollars.

The passes allow that many days of consecutive travel.

• For example, if we get a 7-day pass on day 2, then we can travel for 7 days: 2, 3, 4, 5, 6, 7, and 8.

Return the minimum number of dollars you need to travel every day in the given list of days.

 

Example 1

Input: days = [1,4,6,7,8,20], costs = [2,7,15]

Output: 11

Explanation: For example, here is one way to buy passes that lets you travel your travel plan:

On day 1, you bought a 1-day pass for costs[0] = $2, which covered day 1.

On day 3, you bought a 7-day pass for costs[1] = $7, which covered days 3, 4, ..., 9.

On day 20, you bought a 1-day pass for costs[0] = $2, which covered day 20.

In total, you spent $11 and covered all the days of your travel.

 

Example 2

Input: days = [1,2,3,4,5,6,7,8,9,10,30,31], costs = [2,7,15]

Output: 17

Explanation: For example, here is one way to buy passes that lets you travel your travel plan:

On day 1, you bought a 30-day pass for costs[2] = $15 which covered days 1, 2, ..., 30.

On day 31, you bought a 1-day pass for costs[0] = $2 which covered day 31.

In total, you spent $17 and covered all the days of your travel.

 

Code 

We can solve this by using dynamic programming.

 

This code gets the top 52.81% of the time complexity and uses 14MB of memory.