Submission #366845

#	Time	Username	Problem	Language	Result	Execution time	Memory
366845		mickeyandkaka	Feast (NOI19_feast)	C++17	100 / 100	158 ms	14700 KiB

feast

//{{{
#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using VLL = vector<LL>;
using vi = vector<int>;
using pii = pair<int, int>;
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()
#define clr(a, b) memset(a, b, sizeof(a))
#ifdef LOCAL
#include "prettyprint.hpp"
// clang-format off
void _print() { cerr << "]\033[0m\n"; }
template <typename T> void __print(T x) { cerr << x; }
template <typename T, typename... V> void _print(T t, V... v) { __print(t); if (sizeof...(v)) cerr << ", "; _print(v...); }
#define debug(x...) cerr << "\033[1;34m[" << #x << "] = \033[1;32m["; _print(x)
#define debug_arr(x...) cerr << "\033[1;34m[" << #x << "] = \033[1;32m" << (x) << "\033[0m\n"
#else
#define debug(x...)
#define debug_arr(x...)
#endif
// clang-format on
//}}}

const int N = 3e5 + 10;
// const int N = 10;
int n, k;
LL a[N];
LL s[N];

LL dp[N];
LL cnt[N];

LL minf[N];
LL minf_p[N];

int check(LL c)
{
    dp[0] = 0, cnt[0] = 0;
    minf[0] = dp[0] - s[0];
    minf_p[0] = 0;

    for (int i = 1; i <= n; i++)
    {
        dp[i] = dp[i - 1];
        cnt[i] = cnt[i - 1];

        if (minf[i - 1] + s[i] - c > dp[i])
        {
            dp[i] = minf[i - 1] + s[i] - c;
            // debug(i, dp[i]);

            cnt[i] = cnt[minf_p[i - 1]] + 1;
        }

        else if (minf[i - 1] + s[i] - c == dp[i])
        {
            if (cnt[i] < cnt[minf_p[i - 1]] + 1)
            {
                cnt[i] = cnt[minf_p[i - 1]] + 1;
            }
        }

        minf[i] = minf[i - 1];
        minf_p[i] = minf_p[i - 1];

        if (dp[i] - s[i] > minf[i])
        {
            minf[i] = dp[i] - s[i];
            minf_p[i] = i;
        }
    }
    // if (cnt[n] == 0) return k + 1;
    return cnt[n];
}

// const int NN = 1e3 + 10;
// LL dp2[NN][NN];

int main()
{
#ifdef LOCAL
    freopen("in", "r", stdin);
    // freopen("out", "w", stdout);
#endif

    ios::sync_with_stdio(false);
    cin.tie(0);

    while (cin >> n >> k)
    {
        for (int i = 1; i <= n; ++i) cin >> a[i];
        s[0] = 0;
        for (int i = 1; i <= n; ++i) s[i] = s[i - 1] + a[i];

        // clr(dp2, 0x80);

        // dp2[0][0] = 0;
        // for (int i = 1; i <= n; i++)
        //{
        // dp2[i][0] = 0;
        // for (int j = 1; j <= i; j++)
        //{
        // dp2[i][j] = dp2[i - 1][j];
        // for (int p = 0; p < i; p++)
        //{
        // dp2[i][j] = max(dp2[i][j], dp2[p][j - 1] + s[i] - s[p]);
        //}
        //}
        //}

        // for (int p = 1; p <= n; ++p)
        //{
        // debug(p, dp2[n][p]);
        //}

        // for (int kk = max(1, k - 15); kk <= min(1000, k + 15); kk++)
        //{
        // debug(kk, dp2[n][kk], dp2[n][kk] - dp2[n][kk - 1]);
        //// cout << kk << "," << dp2[n][kk] << endl;
        //}

        // for (int i = -10; i <= 1; i++)
        //{
        // int v = check(i);
        // debug(i, v, cnt[n], dp[n]);
        //}

        LL lo = 0, hi = 1e15;
        bool fd = false;
        while (lo + 1 < hi)
        {
            LL mid = lo + (hi - lo) / 2;

            if (check(mid) >= k)  //最大的Mid >= k
            {
                lo = mid;
                fd = true;
            }
            else
            {
                hi = mid;
            }
        }

        LL c = lo;
        if (check(hi) >= k) c = hi;
        debug(lo, hi, c);

        int v = check(c);
        debug(c, v);
        LL ans = dp[n] + c * k;

        debug(cnt[n], k, dp[n], ans);

        if (!fd)
        {
            LL ans2 = ans;
            v = check(0);
            assert(cnt[n] <= k);
            // assert(dp[n] >= ans);
            if (cnt[n] <= k && dp[n] >= ans) ans2 = dp[n];
            debug(cnt[n], dp[n], ans);
            ans = max(ans, ans2);
        }

        cout << ans << endl;
    }

    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:151:13: warning: variable 'v' set but not used [-Wunused-but-set-variable]
  151 |         int v = check(c);
      |             ^

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29