codeforces AIM Tech Round 3 (Div. 2) B. Checkpoints

Vasya takes part in the orienteering competition. There are n checkpoints located along the line at coordinates x1, x2, ..., xn.
Vasya starts at the point with coordinate a. His goal is to visit at least n - 1 checkpoint
in order to finish the competition. Participant are allowed to visit checkpoints in arbitrary order.

Vasya wants to pick such checkpoints and the order of visiting them that the total distance travelled is minimized. He asks you to calculate this minimum possible value.

Input

The first line of the input contains two integers n and a (1 ≤ n ≤ 100 000,  - 1 000 000 ≤ a ≤ 1 000 000) —
the number of checkpoints and Vasya's starting position respectively.

The second line contains n integers x1, x2, ..., xn ( - 1 000 000 ≤ xi ≤ 1 000 000) —
coordinates of the checkpoints.

Output

Print one integer — the minimum distance Vasya has to travel in order to visit at least n - 1 checkpoint.

题解在这里：http://blog.csdn.net/queuelovestack/article/details/52311222

AC代码：

# include <iostream>
# include <math.h>
# include <stdlib.h>
# include <algorithm>
# include <limits.h>
using namespace std;
int a[100010];
int main(){
int i, j, k, n, b, Min=INT_MAX;
cin>>n>>b;
for(i=1; i<=n; i++){
cin>>a[i];
}
if(n==1){cout<<0;return 0;}
sort(a+1, a+n+1);
if(b<=a[1]){cout<<a[n-1]-b;return 0;}
if(b>=a
){cout<<b-a[2];return 0;}
Min=min(Min, abs(b-a[1])+abs(a[1]-a[n-1]));
Min=min(Min, abs(b-a[2])+abs(a[2]-a
));
Min=min(Min, abs(b-a
)+abs(a
-a[2]));
Min=min(Min, abs(b-a[n-1])+abs(a[n-1]-a[1]));
cout<<Min;
return 0;
}