bzoj3437 小P的牧场

 1 #include<cstdio>
 2 #include<algorithm>
 3 using namespace std;
 4 typedef long long ll;
 5 const int N = 1001010;
 6 int n,i,j,l,r,q[N];
 7 ll f[N],v[N],s[N],a[N];
 8 ll calc(int x,int i)
 9 {
10     return f[x]+a[i]+v[x+1]-v[i]-(n-i)*(s[x+1]-s[i]);
11 }
12 double A(int x,int y)
13 {
14     return f[x]+v[x+1]-f[y]-v[y+1];
15 }
16 double B(int x,int y)
17 {
18     return s[x+1]-s[y+1];
19 }
20 int main()
21 {
22     scanf("%d",&n);
23     for (i=1;i<=n;i++)
24     scanf("%lld",&a[i]);
25     for (i=1;i<=n;i++)
26     scanf("%lld",&s[i]);
27     for (j=n;j>=1;j--)
28     {
29         v[j]=v[j+1]+s[j]*(n-j);
30         s[j]+=s[j+1];
31     }
32     l=1;r=1;
33     for (i=1;i<=n;i++)
34     {
35         while ((l<r)&&(A(q[l],q[l+1])>=B(q[l],q[l+1])*(n-i))) l++;
36         f[i]=calc(q[l],i);
37         while ((l<r)&&(A(q[r],i)*B(q[r-1],q[r])>A(q[r-1],q[r])*B(q[r],i))) r--;
38         r++;q[r]=i;
39     }
40     printf("%lld\n",f[n]);
41 } 
42 //f[x]+v[x+1]-f[y]-v[y+1]>(s[x+1]-s[y+1])*(n-i)
43 //A(y,z)/B(y,z)>A(x,y)/B(x,y)