妙写法

const int N = 2e5 + 10;
int a[N];
int b[N];
int c[N];
int l[N], r[N];
void solve()
{
    int n, m, v;
    cin >> n >> m >> v;
    for (int i = 1; i <= n; i++) cin >> a[i], b[i] = b[i - 1] + a[i];
    int ans = 0;
    int  lh = 0;
    for (int i = 1; i <= n; i++)
    {
        ans += a[i];
        if (ans >= v) l[++lh] = i, ans = 0;
    }

    ans = 0;
    int  rh = 0;
    for (int i = n; i >= 1; i--)
    {
        ans += a[i];
        if (ans >= v) r[++rh] = i, ans = 0;
    }


    if (lh < m && rh < m)
    {
        cout << "-1" << '\n';
        return;
    }
    int mmax = 0;


    r[0] = n + 1;
    //l[m] = 0;
    for (int i = 0; i <= m; i++)
    {
        int x = l[i], y = r[m - i];
        if (x < y) mmax = max(mmax, b[y - 1] - b[x]);
    }
    cout << mmax << '\n';
}