Problem:
Score : 400 points

Problem Statement

You are given N integers; the i-th of them is A_i.
Find the maximum possible sum of the absolute differences between the adjacent elements after arranging these integers in a row in any order you like.

Constraints

2 \leq N \leq 10^5

1 \leq A_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1
:
A_N

Output

Print the maximum possible sum of the absolute differences between the adjacent elements after arranging the given integers in a row in any order you like.

Sample Input 1

5
6
8
1
2
3

Sample Output 1

21

When the integers are arranged as 3,8,1,6,2, the sum of the absolute differences between the adjacent elements is |3 - 8| + |8 - 1| + |1 - 6| + |6 - 2| = 21. This is the maximum possible sum.

Sample Input 2

6
3
1
4
1
5
9

Sample Output 2

25

Sample Input 3

3
5
5
1

Sample Output 3

8

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
void swap(long long int list[], int n, int m){
    long long int tmp = 0;
    tmp = list[m];
    list[m] = list[n];
    list[n] = tmp;
}
long long int find_pivot(long long int list[],int i,int j){
    int k = i + 1;
    while(list[i] == list[k] && k<j){
        k++;
    }
    if(list[i] < list[k]){
        return list[k];
    }else{
        return list[i];
    }
}
long long int partition(long long int list[], int l, int r, long long int pivot){
    while(l <= r){
        while(list[l] < pivot){
            l++;
        }
        while(list[r] >= pivot){
            r--;
        }
        if(l < r){
            swap(list, l, r);
        }
    }
    return l;
}
void quicksort(long long int list[], int i, int j){;
    if(i < j){
        long long int pivot = find_pivot(list, i,j);
        long long k = partition(list, i, j, pivot);
        if(k != i){
            quicksort(list, i, k - 1);
            quicksort(list, k, j);
        }
    }
}
int main(){
  int n;
  scanf("%d\n", &n);
  long long int a[100000];
  int i;
  for(i=0;i<n;i++){
    scanf("%lld",&a[i]);
  }
  quicksort(a,0,n-1);
  long long int ans = 0;
  if(n%2==0){
    for(i=0;i<n/2;i++){
      ans = ans-2*a[i];
    }
    for(i=n/2;i<n;i++){
      ans = ans+2*a[i];
    }
    ans = ans-a[n/2]+a[n/2-1];
  }else{
    int ans1=0;
    int ans2=0;
    for(i=0;i<n/2-1;i++){
      ans1 = ans1-2*a[i];
      ans2 = ans2+2*a[i];
    }
    for(i=n/2+2;i<n;i++){
      ans1 = ans1+2*a[i];
      ans2 = ans2-2*a[i];
    }
    ans1 = ans1-a[n/2]-a[n/2-1]+2*a[n/2+1];
    ans2 = ans2+a[n/2]+a[n/2+1]-2*a[n/2-1];
    if(ans2 > ans1){
      ans = ans2;
    }else{
      ans = ans1;
    }
  }
  printf("%lld\n",ans);
  return 0;
}