bzoj1911 [Apio2010]特别行动队commando

题目链接

斜率优化

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<string>
 4 #include<cstring>
 5 #include<cmath>
 6 #define re(i,l,r) for(int i=(l);i<=(r);i++)
 7 using namespace std;
 8 typedef long long LL;
 9 template<typename Q>
10 void inin(Q &x)
11 {
12     x=0;int f=0;char ch=getchar();
13     while(ch<'0'||ch>'9'){if(ch=='-')f=1;ch=getchar();}
14     while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
15     x=f?-x:x;
16 }
17 int n,a,b,c;
18 LL sum[1000010],x[1000010],y[1000010],aa[1000010],dp[1000010];
19 int q[1000010];
20 LL f(const LL &a){return a*a;}
21 int main()
22 {
23     inin(n);inin(a),inin(b),inin(c);
24     re(i,1,n)inin(aa[i]),sum[i]=sum[i-1]+aa[i];
25     re(i,1,n)x[i]=1LL*a*sum[i];
26     int l=0,r=0;
27     re(i,1,n)
28     {
29         while(l<r&&y[q[l+1]]-y[q[l]]>2LL*sum[i]*(x[q[l+1]]-x[q[l]]))l++;
30         int t=q[l];
31         dp[i]=dp[t]+1LL*f(sum[i]-sum[t])*a+1LL*(sum[i]-sum[t])*b+c;
32         y[i]=dp[i]+1LL*a*f(sum[i])-1LL*b*sum[i];
33         while(l<r&&(y[q[r]]-y[q[r-1]])*(x[i]-x[q[r]])>(y[i]-y[q[r]])*(x[q[r]]-x[q[r-1]]))r--;
34         q[++r]=i;
35     }
36     printf("%lld",dp[n]);
37     return 0;
38 }

 

posted @ 2016-04-03 17:20  HugeGun  阅读(165)  评论(0编辑  收藏  举报