bzoj 3437: 小P的牧场
23333，随便推
1 #include <bits/stdc++.h> 2 #define LL long long 3 #define lowbit(x) x&(-x) 4 #define inf 0x3f3f3f3f 5 #define eps 1e-5 6 #define N 1000005 7 using namespace std; 8 inline LL ra() 9 { 10 LL x=0,f=1; char ch=getchar(); 11 while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();} 12 while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();} 13 return x*f; 14 } 15 LL B[N],sum[N],a[N],b[N],f[N]; 16 int n,q[N]; 17 double slope(int j, int k) 18 { 19 return (f[j]-f[k]-sum[k]+sum[j])/(double)(B[j]-B[k]); 20 } 21 int main() 22 { 23 n=ra(); 24 for (int i=1; i<=n; i++) a[i]=ra(); 25 for (int i=1; i<=n; i++) b[i]=ra(); 26 for (int i=1; i<=n; i++) B[i]=B[i-1]+b[i]; 27 for (int i=1; i<=n; i++) sum[i]=sum[i-1]+(LL)b[i]*i; 28 int l=0,r=0; 29 for (int i=1; i<=n; i++) 30 { 31 while (l<r && slope(q[l+1],q[l])<i) l++; 32 int t=q[l]; 33 f[i]=f[t]+a[i]+(LL)i*(B[i]-B[t])-sum[i]+sum[t]; 34 while (l<r && slope(i,q[r])<slope(q[r],q[r-1])) r--; 35 q[++r]=i; 36 } 37 cout<<f[n]; 38 return 0; 39 }
