bzoj2442: [Usaco2011 Open]修剪草坪(单调队列优化dp)

#include<stdio.h>
#include<algorithm>
using namespace std;
typedef long long ll;
ll n,k;
ll a[100500],sum[100500];
ll dp[100500];
ll que[100500];
int main()
{
scanf("%lld %lld",&n,&k);
for(ll i=1;i<=n;i++)
{
scanf("%lld",&a[i]);
sum[i]=sum[i-1]+a[i];
}
ll f=0,t=1;
que[0]=-1;//取-1的意思是从头取到i。
que[1]=0;
for(ll i=1;i<=n;i++)
{
while(f<=t&&que[f]<i-k-1)f++;
dp[i]=dp[que[f]==-1?0:que[f]]+sum[i]-sum[que[f]+1];
while(f<=t&&dp[que[t]==-1?0:que[t]]-sum[que[t]+1]<=dp[i]-sum[i+1])t--;
que[++t]=i;
}
printf("%lld",dp
);
}