Submission #980715

#	Time	Username	Problem	Language	Result	Execution time	Memory
980715		vjudge1	Rainforest Jumps (APIO21_jumps)	C++17	60 / 100	4041 ms	46588 KiB

jumps

#include <bits/stdc++.h>
#include "jumps.h"

using namespace std;

const int N = 200200;

int n;
int h[N];
int to[N][18][2];

vector<int> g[N];
    
vector<int> bfs(vector<int> st) {
    vector<int> dist(n, 1e9);
    queue<int> q;
    for (int c : st) {
        dist[c] = 0;
        q.push(c);
    }
    while (!q.empty()) {
        int x = q.front();
        q.pop();
        for (int to : g[x]) {
            if (dist[to] > dist[x] + 1) {
                dist[to] = dist[x] + 1;
                q.push(to);
            }
        }
    }
    return dist;
}

bool is1st = true;

void init(int N, vector<int> H) {
    n = N;
    for (int i = 0; i < N; i++) {
        h[i] = H[i];
        is1st &= (h[i] == i + 1);
    }
    
    vector<int> stack;
    for (int i = 0; i < N; i++) {
        while (!stack.empty() && H[stack.back()] < H[i]) 
            stack.pop_back();
        if (stack.empty()) to[i][0][0] = i;
        else to[i][0][0] = stack.back();
        stack.push_back(i);
    }
    stack.clear();
    for (int i = N - 1; i >= 0; i--) {
        while (!stack.empty() && H[stack.back()] < H[i])
            stack.pop_back();
        if (stack.empty()) to[i][0][1] = i;
        else to[i][0][1] = stack.back();
        stack.push_back(i);
    }
    for (int i = 0; i < N; i++) {
        g[i].push_back(to[i][0][0]);
        g[i].push_back(to[i][0][1]);

        if (H[to[i][0][0]] < H[to[i][0][1]])
            swap(to[i][0][0], to[i][0][1]);
    }
    for (int k = 1; k < 18; k++) {
        for (int i = 0; i < N; i++) {
            to[i][k][0] = to[ to[i][k - 1][0] ][k - 1][0];
            to[i][k][1] = to[ to[i][k - 1][1] ][k - 1][1];
        }
    }
}

int minimum_jumps(int A, int B, int C, int D) {
    if (is1st) {
        return C - B;
    }
    if (A == B && C == D) {
        int ans = 0;
        int cur = A;
        for (int k = 17; k >= 0; k--) {
            if (h[to[cur][k][0]] < h[C]) {
                cur = to[cur][k][0];
                ans += (1 << k);
            }
        }
        if (to[cur][0][0] == C) return ans + 1;

        for (int k = 17; k >= 0; k--) {
            if (h[to[cur][k][1]] < h[C]) {
                cur = to[cur][k][1];
                ans += (1 << k);
            }
        }       
        if (to[cur][0][1] == C) return ans + 1;
        return -1;
    }

    vector<int> st;
    for (int i = A; i <= B; i++) st.push_back(i);
    auto dist = bfs(st);
    int res = 1e9;
    for (int i = C; i <= D; i++) 
        res = min(res, dist[i]);
    if (res == 1e9) return -1;
    return res;
}

• 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