记录编号	385426	评测结果	AAAAAAAAAA
题目名称	[SDOI 2016 Round1] 征途	最终得分	100
用户昵称	Marvolo	是否通过	通过
代码语言	C++	运行时间	0.194 s
提交时间	2017-03-21 13:20:32	内存使用	0.34 MiB

#include<cstring>
#include<cstdio>
#include<cctype>
#define N 3010
#define INF 0x3f3f3f3f
using namespace std;

int n,m,i,temp,j,head,tail;
int a[N],f[N],g[N],z[N];

inline int read(){
	int p=0; char c;
	while(c=getchar(),!isdigit(c));
	while(p=(p<<1)+(p<<3)+c-48,c=getchar(),isdigit(c));
	return p;
}

inline int Sqrt(int x){return x*x;}
inline double K(int x,int y){
	return (double)((g[x]-g[y])+Sqrt(a[x])-Sqrt(a[y]))/(double)(a[x]-a[y]);}

int main(){
	freopen("menci_journey.in","r",stdin);
	freopen("menci_journey.out","w",stdout);
	scanf("%d%d",&n,&m);
	for (i=1;i<=n;i++)	scanf("%d",&a[i]),a[i]+=a[i-1];
	memset(f,INF,sizeof(f));	f[0]=0;
	for (j=1;j<=m;j++){
		memcpy(g,f,sizeof(f));	memset(f,0,sizeof(f));
		z[0]=head=tail=0;
		for (i=1;i<=n;i++){
				while (head<tail&&K(z[head+1],z[head])<2*a[i])	head++;
				temp=z[head];
				f[i]=g[temp]+Sqrt(a[i]-a[temp]);
				while (head<tail&&K(z[tail],z[tail-1])>K(z[tail],i))	tail--;
				z[++tail]=i;
		}
	}
	printf("%d\n",m*f[n]-Sqrt(a[n]));
	return 0;
}