Submission #415711

#	Time	Username	Problem	Language	Result	Execution time	Memory
415711		valerikk	Rainforest Jumps (APIO21_jumps)	C++17	31 / 100	4098 ms	48412 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, h[N];
int l[N][L], r[N][L];
int big[N][L];

void build() {
    for (int i = 0; i < n; ++i) {
        l[i][0] = -1;
        r[i][0] = -1;
        big[i][0] = -1;
    }
    vector<int> st;
    for (int i = 0; i < n; ++i) {
        while (!st.empty() && h[st.back()] < h[i]) {
            r[st.back()][0] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    st.clear();
    for (int i = n - 1; i >= 0; --i) {
        while (!st.empty() && h[st.back()] < h[i]) {
            l[st.back()][0] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    st.clear();
    for (int i = 0; i < n; ++i) {
        if (l[i][0] != -1 && (big[i][0] == -1 || h[l[i][0]] > h[big[i][0]])) big[i][0] = l[i][0];
        if (r[i][0] != -1 && (big[i][0] == -1 || h[r[i][0]] > h[big[i][0]])) big[i][0] = r[i][0];
    }
    for (int p = 1; p < L; ++p) {
        for (int i = 0; i < n; ++i) {
            l[i][p] = l[i][p - 1] == -1 ? -1 : l[l[i][p - 1]][p - 1];
            r[i][p] = r[i][p - 1] == -1 ? -1 : r[r[i][p - 1]][p - 1];
            big[i][p] = big[i][p - 1] == -1 ? -1 : big[big[i][p - 1]][p - 1];
        }
    }
}

void init(int n2, vector<int> h2) {
    n = n2;
    for (int i = 0; i < n2; ++i) h[i] = h2[i] - 1;
    build();
}

int get_dist(int s, int t) {
    int res = 0;
    for (int i = L - 1; i >= 0; --i) {
        if (big[s][i] != -1 && h[big[s][i]] <= h[t]) {
            res += (1 << i);
            s = big[s][i];
        }
    }
    for (int i = L - 1; i >= 0; --i) {
        if (r[s][i] != -1 && h[r[s][i]] <= h[t]) {
            res += (1 << i);
            s = r[s][i];
        }
    }
    return s == t ? res : INF;
}

int minimum_jumps(int A, int B, int C, int D) {
    int a = A, b = B, c = C, d = D;
    int res = INF;
    for (int s = a; s <= b; ++s) {
        for (int t = c; t <= d; ++t) res = min(res, get_dist(s, t));
    }
    return res == INF ? -1 : res;
}

#ifdef LOCAL
int main() {
    freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n2, q2;
    cin >> n2 >> q2;
    vector<int> h2(n2);
    for (auto &i : h2) cin >> i;
    init(n2, h2);
    while (q2--) {
        int A, B, C, D;
        cin >> A >> B >> C >> D;
        cout << minimum_jumps(A, B, C, D) << endl;
    }
    return 0;
}
#endif

• Subtask 1: 0 / 4
• Subtask 2: 8 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
• Subtask 5: 23 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19