D. Yet Another Yet Another Task （区间最值）

https://codeforces.com/contest/1359/problem/D

#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <list>
#include <deque>
#include <queue>
#include <stack>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <iomanip>
#define pi acos(-1)
#define ull unsigned long long
#define ll long long
#define pb push_back
#define all(vc) vc.begin() , vc.end()
#define rep(i,start,end) for(int i=start;i<=end;i++)
#define per(i,end,start) for(int i=end;i>=start;i--)
#define tle ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define lc now<<1
#define rc now<<1|1
ll read()
{
    ll x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
using namespace std;
const int mod = 998244353;
const int mxn = 1e6 +7;
const int inf = 1e9;
int _,n,m,t,k,u,v,w,ans,cnt,ok,lim,len,tmp,last,nx;
struct node {int u,v,nx,w;}e[mxn];
string str;
int a[mxn];
void solve()
{
    ans = 0 ;
    for(int i=1;i<=30;i++)
    {
        int nowans = 0 , nowmin = 0 ;
        for(int j=1;j<=n;j++)
        {
            if(a[j]>i){
                nowans = 0 , nowmin = 0 ; continue;
            }
            nowans += a[j] ;
            nowmin = min( nowmin , nowans  );
            ans = max(nowans-nowmin-i , ans);
        }
    }
    cout<<ans<<endl;
}
int main()
{
    tle;
    while(cin>>n)
    {
        for(int i=1;i<=n;i++) cin>>a[i];
        solve();
    }
}