codeforces 1197D Yet Another Subarray Problem

#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long LL;
const int maxn=3e5+2;
int n,m,k;
LL ans=0;
int a[maxn];
LL dp[maxn][10];
void DP(){
    for (int i=n;i;i--)
        for (int j=0;j<m;j++){
            if (j) dp[i][j]=max(0LL,a[i]+dp[i+1][(j+1)%m]);
            else dp[i][j]=max(0LL,dp[i+1][(j+1)%m]+a[i]-k);
            ans=max(ans,dp[i][0]);
        }
}
int main(){
    scanf("%d%d%d%",&n,&m,&k);
    for (int i=1;i<=n;i++) scanf("%d",&a[i]);
    DP();
    printf("%I64d",ans);
    return 0;
}