Leetcode 983. Minimum Cost For Tickets解题报告(python)

1111. 983. Minimum Cost For Tickets

983. Minimum Cost For Tickets python solution

题目描述

In a country popular for train travel, you have planned some train travelling one year in advance. The days of the year that you will travel is given as an array days. Each day is an integer from 1 to 365.
Train tickets are sold in 3 different ways:
a 1-day pass is sold for costs[0] dollars;
a 7-day pass is sold for costs[1] dollars;
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: day 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.

解析

首先理解题目的意思，题目中days数组里的数字，代表着可以出去旅游的日子。并不代表着从哪天开始到哪天结束。
动态规划，详见代码！

// An highlighted block
class Solution:
    def mincostTickets(self, days: List[int], costs: List[int]) -> int:
        days_dict = collections.Counter(days)
        table = [0 for i in range(0, days[-1]+1)]
        
        for i in range(0, days[-1]+1):
            if i not in days_dict:
                table[i] = table[i-1]
            else:
       # Used max to identify if the index exists 
                table[i] = min(
                    table[max(0,i-1)]+costs[0], # per days value
                    table[max(0,i-7)]+costs[1], # per week value
                    table[max(0,i-30)]+costs[2] # per year value
                )
        return table[-1]
         

Reference

https://leetcode.com/problems/minimum-cost-for-tickets/discuss/228421/Python-solution