【hdu3507】Print Article 【斜率优化dp】

题意

https://cn.vjudge.net/problem/HDU-3507

分析

斜率优化的模板题

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <iostream>

 using namespace std;
 typedef long long LL;
 const int maxn=+;
 int n,m;
 int c[maxn],sum[maxn],f[maxn],q[maxn];
 int head,tail;
 int Y(int j){
     return f[j]+sum[j]*sum[j];
 }
 int X(int j){
     return sum[j];
 }

 double grand(int i,int j){
     return (Y(i)-Y(j))/(X(i)-X(j));
 }

 int main(){
     while(scanf("%d%d",&n,&m)!=EOF){
         for(int i=;i<=n;i++){
             scanf("%d",&c[i]);
             sum[i]=sum[i-]+c[i];
         }
         head=tail=;
         q[tail++]=;
         for(int i=;i<=n;i++){
             while(head+<tail&&((Y(q[head+])-Y(q[head]))<=*sum[i]*(X(q[head+])-X(q[head]))))head++;
             f[i]=f[q[head]]+(sum[i]-sum[q[head]])*(sum[i]-sum[q[head]])+m;
 //            printf("%d %d %d\n",i,q[head],f[i]);
 //            printf("%d %d\n",head,tail);
             while(head+<tail&&((Y(q[tail-])-Y(q[tail-]))*(X(i)-X(q[tail-]))>=(X(q[tail-])-X(q[tail-]))*(Y(i)-Y(q[tail-]))))tail--;
             q[tail++]=i;
         }

         printf("%d\n",f[n]);
     }
 return ;
 }