## HopScotch II

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Points: 12 (partial)
Time limit: 2.0s
Java 3.0s
PyPy 2 4.0s
PyPy 3 4.0s
Python 2 12.0s
Python 3 12.0s
Memory limit: 280M
Java 512M
Python 1G

Authors:
Problem types

bruce developed a new hopscotch. In this game, a row of stones conveniently numbered to (inclusive) are set in a pool of lava. As can be expected, the stones are very hot. In fact, they can be hotter than the surface of the sun! bruce must jump from the start () to the other side (), but he can only jump at most stones forward at a time. Fortunately, bruce has a pair of cooling boots that can cool any stone to degrees. However, the boots require one unit of power per degree cooled, and power is very expensive! Can you help bruce find the minimum units of power required to jump to the other side of the lava pool?

bruce can only walk on stones that are degrees.

bruce can only hop forwards to stone () from stone .

Since bruce starts from , he can hop to () on his first hop.

#### Input Specification

The first line will contain and , separated by a space.

The second line will contain all () separated by spaces.

There is a trailing newline (ASCII code 10) at the end of input.

#### Output Specification

Output the minimum power cost to hop from to () on the first line.

Output the indices of the stones bruce must hop on to use the minimum amount of power on the second line, separated by spaces and in ascending order.

If there are multiple ways to achieve the minimum power, output the lexicographically most sequence of the indices.

#### Sample Input 1

16 4
4 5 3 12 2 6 3 6 5 5 16 1 10 9 13 12

#### Sample Output 1

20
3 5 9 12 14

#### Sample Input 2

16 2
4 13 6 6 4 1 7 1 0 15 3 0 8 11 5 8

#### Sample Output 2

32
1 3 5 6 8 9 11 12 13 15

• commented on April 28, 2024, 9:53 a.m.

waste time with "the lexicographically most sequence of the indices", if define it according to my AC submission, it mean "the largest lexicographically of reverse sequence" , example [1, 3, 4] less than [1, 2, 5] because [4, 3, 1] less than [5, 2, 1]

• commented on Aug. 13, 2021, 8:03 a.m. edit 2

I keep TLE on case #7 of final batch, how can I optimise my code

I am using monoqueue + a queue that keeps track of indexes of values in the monoqueue. It is an solution

• commented on Aug. 14, 2021, 4:17 p.m. edited

For some mysterious reason, putting all of my code inside a solve() function significantly increased the speed of my solution. I would recommend that you, and others who are having trouble passing this question in python, try the same.

Edit: I should note that I saw this speedup only when using cpython, not pypy.

• commented on Aug. 16, 2021, 6:51 a.m.

Thank you! My code was indeed sped up, but case 7 still does not pass.

• commented on Feb. 15, 2020, 2:21 a.m. edit 2

What does lexicographically most sequence mean?

Edit: e.g. for the first sample, wouldn't 3 7 10 14 be bigger lexicographically?

• commented on July 27, 2020, 11:02 p.m.

3 7 10 14 would be bigger lexicographically but the total cost would be 3 + 3 + 5 + 10 which is 21 so it isn't the minimum cost

• commented on Feb. 22, 2020, 5:53 p.m.

Why is this downvoted? Assuming "lexicographically most sequence" means "lexicographically largest sequence" the point holds.

• commented on Jan. 9, 2018, 3:13 a.m. edit 3

My solution that uses a monoqueue and a hashmap TLEs and occasionally RTEs (WA aside), why is this solution suboptimal? Can someone give me a hint on how to optimize this?

• commented on March 29, 2018, 1:20 a.m.

No hashmap is needed.