CSU 1529 Equator DP

队列优化DP

Equator

Time Limit: 5000MS

Memory Limit: 131072KB

64bit IO Format: %lld & %llu

Submit Status

Description

Input

Output

Sample Input

3
3 1 2 3
8 4 5 -1 -1 1 -1 -1 5
2 -1 -1

Sample Output

6
14
0

/* ***********************************************
Author        :CKboss
Created Time  :2015年03月17日 星期二 20时13分17秒
File Name     :CSU1529.cpp
************************************************ */

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdlib>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;

const int maxn=2000200;

int n,ans;
int a[maxn];
int sum[maxn];
int dq[maxn],head,tail;

int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);

	int T_T;
	scanf("%d",&T_T);
	while(T_T--)
	{
		scanf("%d",&n);
		for(int i=1;i<=n;i++)
		{
			scanf("%d",a+i); a[n+i]=a[i];
		}
		for(int i=1;i<=2*n;i++)
			sum[i]=sum[i-1]+a[i];
		
		head=0;tail=-1;ans=0;

		for(int i=1;i<=2*n;i++)
		{
			while((head<=tail)&&(sum[i]-sum[dq[tail]]<0))
			{
				ans=max(ans,sum[dq[tail]]-sum[dq[head]]);
				tail--;
			}
			while((head<=tail)&&(i-dq[head]>n))
			{
				ans=max(ans,sum[dq[tail]]-sum[dq[head]]);
				head++;
			}
			dq[++tail]=i;
		}

		printf("%d\n",ans);
	}
    
    return 0;
}