URL: https://www.luogu.org/problem/P1714
Meaning of the questions:
We are given a sequence number $ n-$, $ k interval length is obtained and the maximum value of \ leq m $ a. ($ N \ leq 5e5, m \ leq 5e2 $).
answer:
The title request $ max (sum [i] -sum [j], (0 \ leq ij <m)) $, direct violence seeking will TLE, so we need to optimize data structure, because it is seeking $ max (sum [i ] -sum [j], (0 \ leq ij <m)) $, i.e. $ sum [i] -min (sum [j], j \ in [i-m + 1, i]) $, so monotonically to maintain a minimum incremental queue.
AC Code:
#include <iostream>
#include <algorithm>
#include <and>
using namespace std;
int num [500005];
long long sum[500005];
struct node
{
long long sum;
int pos;
node(long long a,int b)
{
sum=a,pos=b;
}
};
int main ()
{
ios::sync_with_stdio(0);
cin.tie (0);
int n,m;
cin>>n>>m;
for(int i=1;i<=n;++i)
cin>>num[i],sum[i]=sum[i-1]+num[i];
long long ans=-0x3f3f3f3f;
deque<node>maxq;
maxq.push_back(node(sum[0],0));
for(int i=1;i<=n;++i)
{
ans=max(ans,sum[i]-maxq.front().sum);
while(!maxq.empty()&&maxq.back().sum>=sum[i])
maxq.pop_back();
maxq.push_back(node(sum[i],i));
while(maxq.front().pos<i-m+1)
maxq.pop_front();
}
cout<<ans<<endl;
return 0;
}