HNOI2008玩具装箱（T_OY）bzoj1010

//斜率优化DP,详情看程序#include<cctype>#include<cstdio>#include<map>#include<cmath>#include<queue>#include<vector>#include<cstring>#include<cstdlib>#include<iostream>#include<iomanip>#include<algorithm>#define inf 1000000000#define LL long longusing namespace std;LL read(){    LL x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}int n,L,h,t;int c[50005],q[50005];LL s[50005],f[50005],C;double calc(int j,int k){return (f[k]-f[j]+(s[k]+C)*(s[k]+C)-(s[j]+C)*(s[j]+C))/(2.0*(s[k]-s[j]));}int main(){n=read();L=read();C=L+1;for(int i=1;i<=n;i++)c[i]=read();for(int i=1;i<=n;i++)s[i]=s[i-1]+c[i];for(int i=1;i<=n;i++)s[i]+=i;h=1;t=0;q[++t]=0;for(int i=1;i<=n;i++){while(h<t && calc(q[h],q[h+1])<=s[i])h++;int k=q[h];f[i]=f[k]+(s[i]-s[k]-C)*(s[i]-s[k]-C);while(h<t&&calc(q[t],i)<calc(q[t-1],q[t]))t--;q[++t]=i;}printf("%lld\n",f[n]);return 0;}