Poj 3709 K-Anonymous Sequence slope optimization dp

#include <iostream>#include <cstdio>#include <cstring>using namespace std;const int maxn=5e5+9;long long a[maxn];long long dp[maxn],sum[maxn];int que[maxn];bool chk1(int k,int j,int i){    long long s1=(dp[j]-sum[j]+a[j+1]*j)-(dp[k]-sum[k]+a[k+1]*k);    s1*=(a[i+1]-a[j+1]);    long long s2=(dp[i]-sum[i]+a[i+1]*i)-(dp[j]-sum[j]+a[j+1]*j);    s2*=(a[j+1]-a[k+1]);    return s1>s2;}bool chk2(int k,int j,int i){    long long s=(dp[j]-sum[j]+a[j+1]*j)-(dp[k]-sum[k]+a[k+1]*k);    return s<=(a[j+1]-a[k+1])*i;}int main(){//    freopen("in.txt","r",stdin);    int T;    scanf("%d",&T);    while(T--)    {        int n,m;        scanf("%d %d",&n,&m);        sum[0]=0;        for(int i=1;i<=n;i++)        {            scanf("%lld",&a[i]);            a[i]++;            sum[i]=sum[i-1]+a[i];        }        int front=1,end=0;        dp[m]=sum[m]-a[1]*m;        que[++end]=0;        dp[0]=0;        for(int i=1;i+m<=n;i++)        {            if(i>=m)            {                if(a[i+1]==a[que[end]+1])                {                    if(dp[i]<dp[que[end]])                    {                        end--;                        while(front<end&&chk1(que[end-1],que[end],i))                        end--;                        que[++end]=i;                    }                }                else                {                    while(front<end&&chk1(que[end-1],que[end],i))                    end--;                    que[++end]=i;                }            }            while(front<end&&chk2(que[front],que[front+1],i+m))            front++;            int u=que[front];            dp[i+m]=dp[u]+sum[i+m]-sum[u]-a[u+1]*(i+m-u);        }        printf("%lld\n",dp[n]);    }    return 0;}