Submission #711249

#	Time	Username	Problem	Language	Result	Execution time	Memory
711249		Nhoksocqt1	Boxes with souvenirs (IOI15_boxes)	C++17	20 / 100	3 ms	220 KiB

boxes

#include<bits/stdc++.h>
using namespace std;

#define inf 0x3f3f3f3f
#define sz(x) int((x).size())
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> ii;

template<class X, class Y>
	inline bool maximize(X &x, const Y &y) {return (x < y ? x = y, 1 : 0);}
template<class X, class Y>
	inline bool minimize(X &x, const Y &y) {return (x > y ? x = y, 1 : 0);}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Random(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

const int MAXN = 1e7+7;

int a[MAXN], nArr, k, L;

#ifdef Nhoksocqt1

ll delivery(int _N, int _K, int _L, int _pos[]);

int _P[MAXN];

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    freopen("BOXES.inp", "r", stdin);
    freopen("BOXES.out", "w", stdout);

    int N, K, L;
    cin >> N >> K >> L;
    N = Random(1, 10), K = Random(1, N), L = Random(1, 1e9); cout << N << ' ' << K << ' ' << L << '\n';
    for (int i = 0; i < N; ++i)
        cin >> _P[i];

    for (int i = 0; i < N; ++i) _P[i] = Random(0, L - 1); sort(_P, _P + N); for (int i = 0; i < N; ++i) cout << _P[i] << " \n"[i + 1 == N];

    cout << delivery(N, K, L, _P) << '\n';
    return 0;
}

#endif // Nhoksocqt1

ll delivery(int _N, int _K, int _L, int _pos[]) {
    nArr = _N, k = _K, L = _L;

    int cnt0(0);
    while(cnt0 < nArr && _pos[cnt0] == 0)
        ++cnt0;

    for (int i = cnt0 + 1; i <= nArr; ++i)
        a[i - cnt0] = _pos[i - 1];

    nArr = _N - cnt0;

    ll result(0);
    int l(1), r(nArr);
    for (int i = 1; i <= nArr; ++i) {
        if(2 * a[i] >= L)
            break;

        if(i % k == 0) {
            result += 2 * a[i];
            l = i + 1;
        }
    }

    for (int i = nArr; i >= l; --i) {
        if(2 * (L - a[i]) >= L)
            break;

        if((nArr - i + 1) % k == 0) {
            result += 2 * (L - a[i]);
            r = i - 1;
        }
    }

    ll answer(1e18);
    if(r - l >= 0) {
        int cntL(0), cntR(0);
        while(l + cntL <= r && 2 * a[l + cntL] < L)
            ++cntL;

        while(r - cntR >= l && 2 * (L - a[r - cntR]) < L)
            ++cntR;

        int cntM = r - l + 1 - cntL - cntR;
        for (int dem = 0; dem <= cntL; ++dem) {
            int costLeft = (dem > 0 ? min(L, 2 * a[l + dem - 1]) : 0);
            int x = (cntM + cntL - dem + k - 1) / k;
            int costRight = (dem + x * k <= r - l ? min(L, 2 * (L - a[l + dem + x * k])) : 0);

            //cout << costLeft << ' ' << x * L << ' ' << costRight << '\n';
            answer = min(answer, result + costLeft + 1LL * x * L + costRight);
        }
    } else {
        answer = result;
    }

    ll answer2(1e18);
    if(r - l >= 0) {
        int last = min(k, r - l + 1);
        for (int d1 = 0; d1 <= last; ++d1) {
            for (int d2 = 0; d2 <= last && d1 + d2 <= r - l + 1; ++d2) {
                int costLeft = (d1 > 0 ? min(L, 2 * a[l + d1 - 1]) : 0);
                int costRight = (d2 > 0 ? min(L, 2 * (L - a[r - d2 + 1])) : 0);
                ll costMid = (r - l + 1 - d1 - d2 + k - 1) / k * L;
                //cout << d1 << ' ' << d2 << ' ' << costLeft << ' ' << costRight << ' ' << costMid << '\n';
                answer2 = min(answer2, result + costLeft + costMid + costRight);
            }
        }
    } else {
        answer2 = result;
    }

    //cout << answer2 << " FIND: ";
    return answer2;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30