C++ :

#include<cstring>
#include<cstdio>
using namespace std;
#define Size 100010
int n,c,ans=9999999;
int height[Size]={0},tall[Size][110]={0},high[Size][110]={0};
int f[Size][110]={0};
int Abs(int x);
int Min(int x,int y);
int main()
{
	scanf("%d%d",&n,&c);
	int i,j,k,ki,maxhi=0;
	for(i=1;i<=n;i++)
	scanf("%d",&height[i]);
	memset(tall,9999,sizeof(tall));
	memset(high,9999,sizeof(high));
	memset(f,9999,sizeof(f));
	for(j=1;j<=100;j++)
	{
		if(j>=height[1])
			f[1][j]=(j-height[1])*(j-height[1]);
		high[1][j]=Min(high[1][j-1],f[1][j]-j*c);
	}
	for(j=100;j>=1;j--)
	tall[1][j]=Min(tall[1][j+1],f[1][j]+j*c);
	for(i=2;i<=n;i++)
	{
		for(j=1;j<=100;j++)
		{
			if(j>=height[i])
			f[i][j]=Min(tall[i-1][j]-c*j,high[i-1][j]+j*c)+(j-height[i])*(j-height[i]);
			high[i][j]=Min(f[i][j]-j*c,high[i][j-1]);
		}
		for(j=100;j>=1;j--)
		tall[i][j]=Min(f[i][j]+j*c,tall[i][j+1]);
	}
	for(j=1;j<=100;j++)
	ans=Min(ans,f[n][j]);
	printf("%d\n",ans);
	return 0;
}
int Min(int x,int y)
{
	if(x<y)	return x;
	else return y;
}
int Abs(int x)
{
	if(x<0)	return -x;
	else return x;
}