牛客单调队列优化dp刷题小记

烽火传递

#include<bits/stdc++.h>
#define maxn 200005
using namespace std;
int a[maxn],dp[maxn],n,m,ans=0x3f3f3f3f;
deque<int> dq; 
int main(){
	cin>>n>>m;
	dq.push_back(0);
	for(int i=1;i<=n;i++){
		cin>>a[i];
		while(dq.size()&&i-dq.front()>m) dq.pop_front();
		dp[i]=dp[dq.front()]+a[i];
		while(dq.size()&&dp[dq.back()]>dp[i]) dq.pop_back();
		dq.push_back(i);
		if(i>=n-m+1) ans=min(dp[i],ans);
	}
	cout<<ans;
	return 0;
}

修剪草坪

#include<bits/stdc++.h>
using namespace std;
long long n,m,e[100005];
long long dp[100005],s;
long long ans=1e18;
deque<int> dq;
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>e[i];
		s+=e[i];
	} 
	dq.push_back(0);
	for(int i=1;i<=n;i++){
		while(dq.size()&&i-dq.front()>m+1) dq.pop_front();
		dp[i]=dp[dq.front()]+e[i];
		while(dq.size()&&dp[i]<dp[dq.back()]) dq.pop_back();
		dq.push_back(i);
		if(i>n-m-1) ans=min(ans,dp[i]);
	}
	cout<<s-ans;
    return 0;
}