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`

.

**Example 1:**

Input:days = [1,4,6,7,8,20], costs = [2,7,15]Output:11Explanation: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:17Explanation: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.

**Note:**

`1 <= days.length <= 365`

`1 <= days[i] <= 365`

`days`

is in strictly increasing order.`costs.length == 3`

`1 <= costs[i] <= 1000`

```
struct Solution;
impl Solution {
fn mincost_tickets(days: Vec<i32>, costs: Vec<i32>) -> i32 {
let n = days.len();
let mut dp: Vec<i32> = vec![];
let pass = vec![1, 7, 30];
for i in 0..n {
let mut mins = costs.clone();
for k in 0..3 {
for j in (0..i).rev() {
if days[i] - days[j] >= pass[k] {
mins[k] += dp[j];
break;
}
}
}
dp.push(*mins.iter().min().unwrap());
}
dp[n - 1]
}
}
#[test]
fn test() {
let days = vec![1, 4, 6, 7, 8, 20];
let costs = vec![2, 7, 15];
let res = 11;
assert_eq!(Solution::mincost_tickets(days, costs), res);
let days = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31];
let costs = vec![2, 7, 15];
let res = 17;
assert_eq!(Solution::mincost_tickets(days, costs), res);
}
```