hdu 4258 斜率DP

思路：dp[i]=dp[j]+(num[i]-num[j+1])^2;

#include<iostream>

#include<cstring>

#include<algorithm>

#include<cstdio>

#define Maxn 1000010

#define LL unsigned __int64

using namespace std;

LL dp[Maxn],num[Maxn];

int que[Maxn*3];

inline int ReadInt()

{

     char ch = getchar();

     int data = 0;

     while (ch < '0' || ch > '9')

         ch = getchar();

     do

     {

         data = data*10 + ch-'0';

         ch = getchar();

     } while (ch >= '0' && ch <= '9');

     return data;

 }

int main()

{

    int n,i,j;

    LL c;

    while(scanf("%d%I64u",&n,&c)!=EOF,n||c){

        memset(dp,0,sizeof(dp));

        for(i=1;i<=n;i++)

            num[i]=(LL)ReadInt();

        int head,rear;

        head=1;rear=0;

        que[++rear]=0;

        dp[1]=0;

        for(i=1;i<=n;i++){

            while(head<rear&&(dp[que[head+1]]+num[que[head+1]+1]*num[que[head+1]+1]-(dp[que[head]]+num[que[head]+1]*num[que[head]+1])<=2*num[i]*(num[que[head+1]+1]-num[que[head]+1])))

                head++;

            dp[i]=dp[que[head]]+(num[i]-num[que[head]+1])*(num[i]-num[que[head]+1])+c;

            while(head<rear&&(dp[i]+num[i+1]*num[i+1]-(dp[que[rear]]+num[que[rear]+1]*num[que[rear]+1]))*(num[que[rear]+1]-num[que[rear-1]+1])<=(dp[que[rear]]+num[que[rear]+1]*num[que[rear]+1]-(dp[que[rear-1]]+num[que[rear-1]+1]*num[que[rear-1]+1]))*(num[i+1]-num[que[rear]+1]))

                rear--;

            que[++rear]=i;

        }

        printf("%I64u\n",dp[n]);

    }

    return 0;

}