[Usaco2007 Demo]Grazing on the Run

题目描述

A long, linear field has N (1 <= N <= 1,000) clumps of grass at unique integer locations on what will be treated as a number line. Think of the clumps as points on the number line. Bessie starts at some specified integer location L on the number line (1 <= L <= 1,000,000) and traverses the number line in the two possible directions (sometimes reversing her direction) in order to reach and eat all the clumps. She moves at a constant speed (one unit of distance in one unit of time), and eats a clump instantly when she encounters it. Clumps that aren't eaten for a while get stale. We say the ``staleness'' of a clump is the amount of time that elapses from when Bessie starts moving until she eats a clump. Bessie wants to minimize the total staleness of all the clumps she eats. Find the minimum total staleness that Bessie can achieve while eating all the clumps.

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输入格式

* Line 1 : Two space-separated integers: N and L. * Lines 2..N+1: Each line contains a single integer giving the position P of a clump (1 <= P <= 1,000,000).

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输出格式

* Line 1: A single integer: the minimum total staleness Bessie can achieve while eating all the clumps.

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样例输入

4 10
1
9
11
19

INPUT DETAILS:

Four clumps: at 1, 9, 11, and 19. Bessie starts at location 10.

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样例输出

44

OUTPUT DETAILS:

Bessie can follow this route:

* start at position 10 at time 0
* move to position 9, arriving at time 1
* move to position 11, arriving at time 3
* move to position 19, arriving at time 11
* move to position 1, arriving at time 29

giving her a total staleness of 1+3+11+29 = 44.  There are other routes
with the same total staleness, but no route with a smaller one.

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提示

没有写明提示

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题目来源

Gold