BZOJ 3675 [Apio2014]序列分割

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=100009;
const int maxm=209;
typedef long long Lint;


int n,m;
Lint s[maxn];
int ref[maxn];

Lint f[maxn];
Lint g[maxn];

int p[maxn][maxm];

int q[maxn];
Lint Getk(int i){
	return g[i]-s[i]*s[i];
}

void putans(int x,int y){
	if(y==0)return;
	putans(p[x][y],y-1);
	printf("%d ",ref[x]);
}

int main(){
	scanf("%d%d",&n,&m);++m;
	int cnt=0;
	for(int i=1;i<=n;++i){
		Lint x;
		scanf("%lld",&x);
		if(x==0)continue;
		++cnt;
		s[cnt]=s[cnt-1]+x;
		ref[cnt]=i;
	}
	n=cnt;
	
	int h,t;
	for(int j=2;j<=m;++j){
		q[h=t=1]=j-1;
		for(int i=j;i<=n;++i){
			while((h<t)&&((Getk(q[h+1])-Getk(q[h]))>-s[i]*(s[q[h+1]]-s[q[h]])))++h;
//			printf("%d %d %d\n",j,i,q[h]);
			f[i]=g[q[h]]+(s[i]-s[q[h]])*s[q[h]];
			p[i][j]=q[h];
			while(h<t){
				int a=q[t-1],b=q[t];
				if(1.0*(Getk(b)-Getk(a))/(s[b]-s[a])<1.0*(Getk(i)-Getk(b))/(s[i]-s[b]))--t;
				else break;
			}
			q[++t]=i;
		}
		for(int i=1;i<=n;++i){
			g[i]=f[i];f[i]=0;
		}
	}
	
	printf("%lld\n",g[n]);
//	putans(p[n][m],m-1);
//	printf("\n");
	
	return 0;
}