poj 3709 K-Anonymous Sequence 斜率优化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
);
}
return 0;
}