Algorithm
Problem Name: 983. Minimum Cost For Tickets
Problem Link: https://leetcode.com/problems/minimum-cost-for-tickets/
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 for7days:2,3,4,5,6,7, and8.
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.
Constraints:
1 <= days.length <= 3651 <= days[i] <= 365daysis in strictly increasing order.costs.length == 31 <= costs[i] <= 1000
Code Examples
#1 Code Example with Javascript Programming
Code -
Javascript Programming
const mincostTickets = function(days, costs) {
const last7 = [], last30 = []
let res = 0
for(let d of days) {
while(last7.length && last7[0][0] + 7 <= d) last7.shift()
while(last30.length && last30[0][0] + 30 <= d) last30.shift()
last7.push([d, res + costs[1]])
last30.push([d, res + costs[2]])
res = Math.min(res + costs[0], last7[0][1], last30[0][1])
}
return res
};
Input
days = [1,4,6,7,8,20], costs = [2,7,15]
Output
11
#2 Code Example with Python Programming
Code -
Python Programming
class Solution:
def mincostTickets(self, days: List[int], costs: List[int]) -> int:
day, days, last = [0] * 366, set(days), days[-1]
for i in range(1, last + 1):
if i not in days:
day[i] = day[i - 1]
else:
day[i] = min(day[i - 1] + costs[0], day[i - 7 if i>= 7 else 0] + costs[1], day[i - 30 if i >= 30 else 0] + costs[2])
return day[last]
Input
days = [1,4,6,7,8,20], costs = [2,7,15]
Output
11
#3 Code Example with C# Programming
Code -
C# Programming
using System;
namespace LeetCode
{
public class _0983_MinimumCostForTickets
{
public int MincostTickets(int[] days, int[] costs)
{
var memo = new int?[days.Length];
return DP(0, days, costs, memo, new int[] { 1, 7, 30 });
}
private int DP(int index, int[] days, int[] costs, int?[] memo, int[] duration)
{
if (index >= days.Length) return 0;
if (memo[index].HasValue) return memo[index].Value;
var result = int.MaxValue;
var index2 = index;
for (int type = 0; type < 3; type++)
{
while (index2 < days.Length && days[index2] < days[index] + duration[type])
index2++;
result = Math.Min(result, DP(index2, days, costs, memo, duration) + costs[type]);
}
memo[index] = result;
return result;
}
}
}
Input
days = [1,2,3,4,5,6,7,8,9,10,30,31], costs = [2,7,15]
Output
17