Submission #416420

#	Time	Username	Problem	Language	Result	Execution time	Memory
416420		valerikk	Rainforest Jumps (APIO21_jumps)	C++17	100 / 100	1575 ms	41364 KiB

jumps

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef long double ld;

const int N = 2e5 + 7;
const int L = 19;
const int INF = 1e9;

int n;
int h[N];
pair<int, int> t[4 * N];

void tree_build(int v, int l, int r) {
    if (r - l == 1) {
        t[v] = {h[l], l};
    } else {
        int mid = (l + r) / 2;
        tree_build(2 * v, l, mid);
        tree_build(2 * v + 1, mid, r);
        t[v] = max(t[2 * v], t[2 * v + 1]);
    }
}

pair<int, int> get_max(int v, int l, int r, int a, int b) {
    if (l >= b || r <= a) return {-INF, -INF};
    if (l >= a && r <= b) return t[v];
    int mid = (l + r) / 2;
    return max(get_max(2 * v, l, mid, a, b), get_max(2 * v + 1, mid, r, a, b));
}

int find_first(int v, int l, int r, int a, int b, int val) {
    if (l >= b || r <= a || t[v].first <= val) return -1;
    if (r - l == 1) return l;
    int mid = (l + r) / 2;
    int res = find_first(2 * v + 1, mid, r, a, b, val);
    if (res == -1) res = find_first(2 * v, l, mid, a, b, val);
    return res;
}

vector<vector<int>> build(vector<int> arr) {
    vector<vector<int>> go(L, vector<int>(n));
    for (int i = 0; i < n; ++i) go[0][i] = arr[i];
    for (int i = 1; i < L; ++i) {
        for (int j = 0; j < n; ++j) go[i][j] = go[i - 1][go[i - 1][j]];
    }
    return go;
}

vector<int> l, r, best;
vector<vector<int>> r2, best2;

void init(int N, vector<int> H) {
    n = N + 2;
    h[0] = n - 2;
    h[n - 1] = n - 1;
    for (int i = 0; i < N; ++i) h[i + 1] = H[i] - 1;
    l.resize(n);
    r.resize(n);
    best.resize(n);
    vector<int> st;
    for (int i = 0; i < n; ++i) {
        while (!st.empty() && h[st.back()] < h[i]) {
            r[st.back()] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    for (auto i : st) r[i] = n - 1;
    st.clear();
    for (int i = n - 1; i >= 0; --i) {
        while (!st.empty() && h[st.back()] < h[i]) {
            l[st.back()] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    for (auto i : st) l[i] = 0;
    st.clear();
    for (int i = 0; i < n; ++i) best[i] = h[l[i]] > h[r[i]] ? l[i] : r[i];
    r2 = build(r);
    best2 = build(best);
    tree_build(1, 0, n);
}

int minimum_jumps(int A, int B, int C, int D) {
    ++A, ++B, ++C, ++D;
    int mx = get_max(1, 0, n, C, D + 1).first;
    int mx2 = get_max(1, 0, n, B + 1, C).first;
    //cout << A << " " << B << " " << C << " " << D << " " << mx << " " << mx2 << " " << h[B] << endl;
    if (h[B] > mx || mx2 > mx) return -1;
    int min_pos = find_first(1, 0, n, 0, B + 1, mx);
    A = max(A, min_pos + 1);
    int st = get_max(1, 0, n, A, B + 1).second;
    int id = st, res = 0;
    for (int i = L - 1; i >= 0; --i) {
        if (h[best2[i][id]] < mx2) {
            id = best2[i][id];
            res += (1 << i);
        }
    }
    if (h[id] < mx2 && h[best[id]] < mx) {
        id = best[id];
        ++res;
    }
    for (int i = L - 1; i >= 0; --i) {
        if (h[r2[i][id]] < mx2) {
            id = r2[i][id];
            res += (1 << i);
        }
    }
    if (h[id] < mx2) {
        id = r[id];
        ++res;
    }
    /*while (h[id] < mx2) {
        ++res;
        if (h[best[id]] < mx) id = best[id]; else id = r[id];
    }*/
    id = r[id];
    ++res;
    //assert(id >= C && id <= D);
    return res;
}

int correct_minimum_jumps(int A, int B, int C, int D) {
    ++A, ++B, ++C, ++D;
    vector<int> dist(n, INF);
    vector<int> q;
    for (int i = A; i <= B; ++i) {
        q.push_back(i);
        dist[i] = 0;
    }
    for (int i = 0; i < q.size(); ++i) {
        int v = q[i];
        if (dist[v] + 1 < dist[l[v]]) {
            dist[l[v]] = dist[v] + 1;
            q.push_back(l[v]);
        }
        if (dist[v] + 1 < dist[r[v]]) {
            dist[r[v]] = dist[v] + 1;
            q.push_back(r[v]);
        }
    }
    int mn = INF;
    for (int i = C; i <= D; ++i) mn = min(mn, dist[i]);
    return mn == INF ? -1 : mn;
}

#ifdef LOCAL
int main() {
    freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(false);
    cin.tie(0);
    if (0) {
        int N, Q;
        cin >> N >> Q;
        vector<int> H(N);
        for (int i = 0; i < N; ++i) cin >> H[i];
        init(N, H);
        while (Q--) {
            int A, B, C, D;
            cin >> A >> B >> C >> D;
            cout << minimum_jumps(A, B, C, D) << endl;
        }
    } else {
        srand(0);
        int N = 12, Q = 100000;
        vector<int> H(N);
        iota(H.begin(), H.end(), 1);
        random_shuffle(H.begin(), H.end());
        init(N, H);
        while (Q--) {
            vector<int> v;
            for (int i = 0; i < 4; ++i) v.push_back(rand() % N);
            sort(v.begin(), v.end());
            if (v[1] == v[2]) continue;
            int A = v[0], B = v[1], C = v[2], D = v[3];
            int ans = minimum_jumps(A, B, C, D);
            int correct_ans = correct_minimum_jumps(A, B, C, D);
            if (ans != correct_ans) {
                cout << N << " 1" << endl;
                for (int i = 0; i < N; ++i) cout << H[i] << " ";
                cout << endl;
                cout << A << " " << B << " " << C << " " << D << endl;
                cout << ans << " " << correct_ans << endl;
                return 0;
            }
        }
    }
    return 0;
}
#endif

Compilation message (stderr)

jumps.cpp: In function 'int correct_minimum_jumps(int, int, int, int)':
jumps.cpp:135:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  135 |     for (int i = 0; i < q.size(); ++i) {
      |                     ~~^~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 12 / 12
• Subtask 5: 23 / 23
• Subtask 6: 21 / 21
• Subtask 7: 19 / 19