HDU 3507

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#define N 500050
using namespace std;

int dp[N],su[N],q[N+100];
int head,tail;

int UP(int j,int k){
	return dp[j]+su[j]*su[j]-dp[k]-su[k]*su[k];
}

int DOWN (int j,int k){
	return 2*su[j]-2*su[k];
}

int main(){
	int n,m,tmp;
	su[0]=0;
	while(scanf("%d%d",&n,&m)!=EOF){
		head=tail=0;
		for(int i=1;i<=n;i++){
			scanf("%d",&tmp);
			su[i]=tmp+su[i-1];
		}
		memset(dp,0,sizeof(dp));
		q[0]=0; tail=1;
		for(int i=1;i<=n;i++){
			while(head<tail-1&&UP(q[head+1],q[head])<=DOWN(q[head+1],q[head])*su[i])
			head++;
			dp[i]=dp[q[head]]+(su[i]-su[q[head]])*(su[i]-su[q[head]])+m;
			while(head<tail-1&&UP(i,q[tail-1])*DOWN(q[tail-1],q[tail-2])<=UP(q[tail-1],q[tail-2])*DOWN(i,q[tail-1]))
			tail--;
			q[tail++]=i;
		}
		printf("%d\n",dp[n]);
	}
	return 0;
}