[codeforces1016c] vasya and the mushrooms (dp)

using namespace std;

using LL = long long;
const int maxn = 300003;
int dx[5] = {0, 0, 1, -1};
int dy[5] = {1, -1, 0, 0};
int n;
LL a[maxn], b[maxn];
LL sa[maxn], sb[maxn], ia[maxn], ib[maxn], da[maxn], db[maxn];

signed () {
  
  while(~scanf("%d", &n)) {
    for(int i = 0; i < n; i++) scanf("%lld",&a[i]);
    for(int i = 0; i < n; i++) scanf("%lld",&b[i]);
    memset(sa, 0, sizeof(sa));
    memset(sb, 0, sizeof(sb));
    memset(ia, 0, sizeof(ia));
    memset(ib, 0, sizeof(ib));
    memset(da, 0, sizeof(da));
    memset(db, 0, sizeof(db));
    for(int i = n - 1; i >= 0; i--) {
      sa[i] = sa[i+1] + a[i];
      sb[i] = sb[i+1] + b[i];
      ia[i] = ia[i+1] + a[i] * (LL)(n-i-1LL);
      ib[i] = ib[i+1] + b[i] * (LL)(n-i-1LL);
      da[i] = da[i+1] + a[i] * (LL)i;
      db[i] = db[i+1] + b[i] * (LL)i;
    }
    LL ret = 0, tmp = 0;
    for(int i = 0; i < n; i++) {
      if(i & 1) {
        LL tr = db[i] + sb[i] * (2LL*i - i);
        tr += ia[i] + sa[i] * (2LL*i + n - i);
        ret = max(ret, tmp+tr);
        tmp += (2LL*i*b[i]);
        tmp += (2LL*i+1LL)*a[i];
      }
      else {
        LL tr = da[i] + sa[i] * (2LL*i - i);
        tr += ib[i] + sb[i] * (2LL*i + n - i);
        ret = max(ret, tmp+tr);
        tmp += (2LL*i*a[i]);
        tmp += (2LL*i+1LL)*b[i];
      }
    }
    printf("%lldn", ret);
  }
  return 0;
}