bzoj1010

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cmath>
 4 #include<ctime>
 5 #include<cstdlib>
 6 #include<iostream>
 7 #include<algorithm>
 8 #define clr(a,x) memset(a,x,sizeof(a))
 9 #define rep(i,l,r) for(int i=l;i<r;i++)
10 typedef long long ll;
11 using namespace std;
12 int read()
13 {
14     char c=getchar();
15     int ans=0,f=1;
16     while(!isdigit(c)){
17         if(c==‘-‘) f=-1;
18         c=getchar();
19     }
20     while(isdigit(c)){
21         ans=ans*10+c-‘0‘;
22         c=getchar();
23     }
24     return ans*f;
25 }
26 #define A(i) (s[i]+i)
27 #define B(i) (A(i)+1+l)
28 #define X(k,j) (d[k]+B(k)*B(k)-d[j]-B(j)*B(j))
29 #define Y(k,j) (B(k)-B(j))
30 const int maxn=50050,inf=0x3fffffff;
31 ll c[maxn],s[maxn],d[maxn],q[maxn];
32 int main()
33 {    
34     clr(c,0),clr(s,0),clr(d,0),clr(q,0);
35     ll n=read(),l=read();
36     rep(i,1,n+1){
37         c[i]=read();
38         d[i]=inf;
39     }
40     s[1]=c[1];
41     rep(i,2,n+1) s[i]=s[i-1]+c[i];
42     int front=0,rear=0;
43     rep(i,1,n+1){
44         while(rear>front&&(X(q[front+1],q[front])<=Y(q[front+1],q[front])*2*A(i))) front++;
45         d[i]=d[q[front]]+(A(i)-B(q[front]))*(A(i)-B(q[front]));
46         while(rear>front&&X(i,q[rear])*Y(q[rear],q[rear-1])*2<=X(q[rear],q[rear-1])*Y(i,q[rear])*2) rear--;
47         q[++rear]=i;
48     }
49     printf("%lld\n",d[n]);
50     return 0;
51 }