HDU3507-Print Article-斜率dp入门题

为了学CDQ分治，从斜率dp和凸包开始做吧。。

代码就是维护一个凸包。利用递增的性质丢掉不合适的点。

http://www.cnblogs.com/Rlemon/p/3184899.html

代码学的上面 很模板

 #include <cstdio>
 #include <algorithm>

 using namespace std;
 //typedef long long LL;

 struct Point{
     int x,y;
     Point (int _x=,int _y=):x(_x),y(_y){}
     Point operator - (const Point &rhs) const
     {
         return Point(x-rhs.x,y-rhs.y);
     }
 };
 typedef Point Vector;
 inline int Cross(const Vector &u,const Vector &v)
 {
     return u.x*v.y - u.y*v.x;
 }

 const int maxn = 5e5+;
 int N,M;
 int sum[maxn],save[maxn];
 int dp[maxn];
 struct dequeue{
     Point q[maxn];
     int head,tail;
     void init()
     {
         head = ;tail = ;
         //q[head].x = 0;q[head].y = 0;
     }
     void push(const Point &u)
     {
         while(head < tail && Cross(q[tail]-q[tail-],u-q[tail])<=) tail--;
         q[++tail] = u;
     }
     Point pop(const int &k)
     {
         while(head < tail && k*q[head].x+q[head].y >= k*q[head+].x + q[head+].y) head++;
         //printf("head:%d x:%d y:%d\n",head,q[head].x,q[head].y);
         return q[head];
     }
 }H;

 int main()
 {
     //freopen("input.txt","r",stdin);
     while(~scanf("%d%d",&N,&M))
     {
         sum[] = ;
         for(int i=;i<=N;i++)
         {
             scanf("%d",&save[i]);
             sum[i] = sum[i-]+save[i];
         }
         H.init();
         H.push(Point(,));
         dp[] = ;
         for(int i=;i<=N;i++)
         {
             int k = -*sum[i];
             Point u = H.pop(k);
             //printf("i:%d k:%d u.x:%d u.y:%d\n",i,k,u.x,u.y);
             dp[i] = u.x*k + u.y + sum[i]*sum[i] + M;
             H.push(Point(sum[i],dp[i]+sum[i]*sum[i]));
             //printf("push:%d %d\n",sum[i],dp[i]+sum[i]*sum[i]);
         }
         printf("%d\n",dp[N]);
     }
 }