UValive4195 Heroes of Money and Magic

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<iostream>
 4 #include<string>
 5 #include<cstring>
 6 #define Clear(x,i) memset(x,i,sizeof(x))
 7 #define re(i,l,r) for(int i=(l);i<=(r);i++)
 8 #define rre(i,r,l) for(int i=(r);i>=(l);i--)
 9 using namespace std;
10 template <typename Q>
11 void inin(Q &ret)
12 {
13     ret=0;int f=0;char ch=getchar();
14     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=1;ch=getchar();}
15     while(ch>=‘0‘&&ch<=‘9‘)ret=(ret<<3)+(ret<<1)+ch-‘0‘,ch=getchar();
16     ret=f?-ret:ret;
17 }
18 int n,m,a[5010],sum[5010],cost[5010],x[5010][2],y[5010][2],num[2];
19 int f[5010][2],c;
20 int cross(int a,int b,int xx,int yy)
21 {
22     return (x[b][c]-x[a][c])*(yy-y[a][c])-
23            (xx-x[a][c])*(y[b][c]-y[a][c]);
24 }
25 int main()
26 {
27     while(scanf("%d%d",&n,&m),n)
28     {
29         m++;
30         for(int i=1;i<=n;i++)
31         {
32             scanf("%d",&a[i]);
33             sum[i]=sum[i-1]+a[i];
34             cost[i]=cost[i-1]+sum[i-1]*a[i];
35         }
36         num[1]=0;
37         c=1;
38         x[1][1]=y[1][1]=0;
39         for(int j=1;j<=m;j++)
40         {
41             c^=1;
42             num[c]=0;
43             for(int i=1,k=1;i<=n;i++)
44             {
45                 while(k<num[!c]&&(x[k+1][!c]-x[k][!c])*sum[i]>y[k+1][!c]-y[k][!c])k++;
46                 f[i][c]=-sum[i]*x[k][!c]+y[k][!c]+cost[i];
47                 int xx=sum[i],yy=f[i][c]+xx*xx-cost[i];
48                 while(1<num[c]&&cross(num[c]-1,num[c],xx,yy)<=0)num[c]--;
49                 x[++num[c]][c]=xx;
50                 y[num[c]][c]=yy;
51             }
52         }
53         printf("%d\n",f[n][c]);
54     }
55     return 0;
56 }