Submission #744780

#	Time	Username	Problem	Language	Result	Execution time	Memory
744780		t6twotwo	Rainforest Jumps (APIO21_jumps)	C++17	60 / 100	4066 ms	55176 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
using namespace std;
int N;
vector<int> H;
bool subtask1;
vector<vector<int>> adj, hi, lo;
void init(int n, vector<int> h) {
    N = n, H = h;
    subtask1 = 1;
    for (int i = 0; i < N; i++) {
        H[i]--;
        if (i != H[i]) {
            subtask1 = 0;
        }
    }
    adj.resize(N);
    vector<int> stk;
    for (int i = N - 1; i >= 0; i--) {
        while (!stk.empty() && H[stk.back()] < H[i]) {
            stk.pop_back();
        }
        if (!stk.empty()) {
            adj[H[i]].push_back(H[stk.back()]);
        }
        stk.push_back(i);
    }
    stk.clear();
    for (int i = 0; i < N; i++) {
        while (!stk.empty() && H[stk.back()] < H[i]) {
            stk.pop_back();
        }
        if (!stk.empty()) {
            adj[H[i]].push_back(H[stk.back()]);
        }
        stk.push_back(i);
    }
    lo.resize(N + 1, vector<int>(18, N));
    hi.resize(N + 1, vector<int>(18, N));
    for (int i = 0; i < N; i++) {
        if (adj[i].size() == 1) {
            hi[i][0] = adj[i][0];
        }
        if (adj[i].size() == 2) {
            tie(lo[i][0], hi[i][0]) = minmax(adj[i][0], adj[i][1]);
        }
    }
    for (int j = 0; j < 17; j++) {
        for (int i = 0; i < N; i++) {
            lo[i][j + 1] = lo[lo[i][j]][j];
            hi[i][j + 1] = hi[hi[i][j]][j];
        }
    }
}
int minimum_jumps(int A, int B, int C, int D) {
    if (subtask1) {
        return C - B;
    }
    if (A == B && C == D) {
        int x = H[A];
        int y = H[C];
        int ans = 0;
        for (int i = 17; i >= 0; i--) {
            if (hi[x][i] <= y) {
                ans += 1 << i;
                x = hi[x][i];
            }
        }
        for (int i = 17; i >= 0; i--) {
            if (lo[x][i] <= y) {
                ans += 1 << i;
                x = lo[x][i];
            }
        }
        if (x != y) {
            ans = -1;
        }
        return ans;
    }
    vector<int> dis(N, N);
    queue<int> q;
    for (int i = A; i <= B; i++) {
        dis[H[i]] = 0;
        q.push(H[i]);
    }
    while (!q.empty()) {
        int x = q.front();
        q.pop();
        for (int y : adj[x]) {
            if (dis[y] == N) {
                dis[y] = dis[x] + 1;
                q.push(y);
            }
        }
    }
    int ans = N;
    for (int i = C; i <= D; i++) {
        ans = min(ans, dis[H[i]]);
    }
    if (ans == N) {
        ans = -1;
    }
    return ans;
}

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