[HYSBZ][1010][玩具装箱toy]

题目：http://acm.hust.edu.cn:8080/judge/problem/viewProblem.action?id=16331

View Code

#include <stdio.h>

#include <string.h>

#include <math.h>

#include <algorithm>



#define ll long long

#define clr(a,b) memset(a, b, sizeof(a))

using namespace std;



const int N = 50000+10;

const int M = 10000+10;

const int inf = 0x3f3f3f3f;



ll n, m, l, r;

ll a[N], dp[N], q[N];



ll sqr(ll a){return a*a;}



void input()

{

    a[0] = dp[0] = 0;

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

        scanf("%d", &a[i]), a[i]+=a[i-1];

}



ll dy(ll k1, ll k2)

{

    return dp[k1]-dp[k2]+sqr(k1+a[k1]+m+1)-sqr(k2+a[k2]+m+1);

}



ll dx(ll k1, ll k2)

{

    return k1+a[k1]-k2-a[k2];

}



int main()

{

    //freopen("D:/a.txt", "r", stdin);

    while (~scanf("%lld%lld", &n, &m))

    {

        input();

        q[l=r=0] = 0;

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

        {

            while (l<r && dy(q[l],q[l+1])>=2*(i+a[i])*dx(q[l],q[l+1]))l++;

            dp[i] = dp[q[l]] + sqr(i-q[l]-1+a[i]-a[q[l]]-m);

            while (l<r && dy(q[r-1],q[r])*dx(q[r],i)>=dy(q[r],i)*dx(q[r-1],q[r]))r--;

            q[++r]=i;

        }

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

    }

    return 0;

}