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30726
斜率优化。
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<functional>
#include<iostream>
#include<cmath>
#include<cctype>
#include<ctime>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=pre[x];p;p=next[p])
#define Lson (x<<1)
#define Rson ((x<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,127,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define INF (2139062143)
#define F (100000007)
#define MAXN (1000000+10)
#define eps 1e-13
#define Read(x) { while (!isdigit(c=getchar())); x=c-48; while (isdigit(c=getchar())) x=x*10+c-48; }
long long mul(long long a,long long b){return (a*b)%F;}
long long add(long long a,long long b){return (a+b)%F;}
long long sub(long long a,long long b){return (a-b+(a-b)/F*F+F)%F;}
typedef long long ll;
int n;
ll cost;
char c;
ll a[MAXN],f[MAXN];
struct P
{
int i;
long double x,y;
P(int _i,ll _x,ll _y):i(_i),x(_x),y(_y){}
P(ll _x,ll _y):x(_x),y(_y){}
P(){}
friend long double kk(P a,P b){if (abs(a.x-b.x)<eps) return (b.y-a.y)*INF;return (b.y-a.y)/(b.x-a.x); }
}st[MAXN];
struct V
{
long double x,y;
V(ll _x,ll _y):x(_x),y(_y){}
V(){}
V(P a,P b):x(b.x-a.x),y(b.y-a.y){}
friend long double operator*(V a,V b){return a.x*b.y-a.y*b.x; }
};
int main()
{
freopen("B.in","r",stdin);
while (1)
{
scanf("%d%lld",&n,&cost);
if (!n) break;
For(i,n)
Read(a[i])
f[0]=0;
int head=1,tail=1;
st[1]=P(1,a[1],a[1]*a[1]);
Fork(i,1,n)
{
P A=P(i,a[i],f[i-1]+a[i]*a[i]);
while (head^tail&&V(st[tail-1],st[tail])*V(st[tail],A)<=0) tail--;
st[++tail]=A;
while (head^tail&&kk(st[head],st[head+1])<2*a[i]) head++;
int k=st[head].i;
f[i]=f[k-1]+cost+(a[k]-a[i])*(a[k]-a[i]);
}
cout<<f[n]<<endl;
}
return 0;
}
版权声明：本文为博主原创文章，未经博主允许不得转载。
HDU 4258(Covered Walkway-斜率优化)
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原文地址：http://blog.csdn.net/nike0good/article/details/47610799
