Submission #802992

#	Time	Username	Problem	Language	Result	Execution time	Memory
802992		andreiomd	Fountain (eJOI20_fountain)	C++14	0 / 100	2 ms	340 KiB

fountain

#include <iostream>
#include <stack>

using namespace std;
using PII = pair<int, int>;

static constexpr int NMAX = (int)(1e5 + 1), LOGMAX = 17;

int N, Q;
int D[NMAX], C[NMAX];

PII Next[LOGMAX][NMAX];

static inline void Read()
{
    freopen("fountain.in", "r", stdin);
    freopen("fountain.out", "w", stdout);
    ios_base ::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> N >> Q;
    for (int i = 1; i <= N; ++i)
        cin >> D[i] >> C[i], Next[0][i] = {0, 0};

    return;
}

static inline void Get_level_0()
{
    stack<int> S;

    for (int i = 1; i <= N; ++i)
    {
        while (!S.empty() && D[i] > D[S.top()])
            Next[0][S.top()].first = i, Next[0][S.top()].second += C[i], S.pop();

        S.push(i);
    }

    return;
}

static inline void Precompute()
{
    for (int i = 1; (1 << i) <= N; ++i)
        for (int j = 1; j <= N; ++j)
            Next[i][j] = {Next[i - 1][Next[i - 1][j].first].first, Next[i - 1][j].second + Next[i - 1][Next[i - 1][j].first].second};

    return;
}

static inline void Test_Case()
{
    int node = 0, target = 0;
    cin >> node >> target;

    if (C[node] >= target)
    {
        cout << node << '\n';
        return;
    }

    if (!Next[0][node].first)
    {
        cout << 0 << '\n';
        return;
    }

    target -= C[node];

    for (int i = 16; i >= 0; --i)
        if (Next[i][node].first)
            if (target - Next[i][node].second >= 0)
                target -= Next[i][node].second, node = Next[i][node].first;

    if (target == 0)
        cout << node;
    else
        cout << Next[0][node].first;

    cout << '\n';

    return;
}

static inline void Solve()
{
    for (int q = 1; q <= Q; ++q)
        Test_Case();

    return;
}

int main()
{
    Read();

    Get_level_0();

    Precompute();

    Solve();

    return 0;
}

Compilation message (stderr)

fountain.cpp: In function 'void Read()':
fountain.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen("fountain.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
fountain.cpp:17:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     freopen("fountain.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40