Submission #555973

#	Time	Username	Problem	Language	Result	Execution time	Memory
555973		joelau	Rainforest Jumps (APIO21_jumps)	C++14	100 / 100	1170 ms	66104 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
using namespace std;

int n, p1[200005][20], p2[200005][20], p3[200005][20], p4[200005][20], X[200005];
stack<int> s;

void init(int N, std::vector<int> H) {
    n = N;
    for (int i = 0; i < N; ++i) X[i] = H[i];
    memset(p1,-1,sizeof(p1));
    memset(p2,-1,sizeof(p2));
    memset(p3,-1,sizeof(p3));
    memset(p4,-1,sizeof(p4));
    for (int i = 0; i < N; ++i) {
        while (!s.empty() && H[i] >= H[s.top()]) s.pop();
        if (!s.empty()) p1[i][0] = p3[i][0] = s.top();
        s.push(i);
    }
    while (!s.empty()) s.pop();
    for (int i = N-1; i >= 0; --i) {
        while (!s.empty() && H[i] >= H[s.top()]) s.pop();
        if (!s.empty()) p2[i][0] = p4[i][0] = s.top();
        s.push(i);
    }
    for (int i = 0; i < N; ++i) if (p1[i][0] == -1 || (p1[i][0] != -1 && p2[i][0] != -1 && H[p1[i][0]] < H[p2[i][0]])) swap(p1[i][0], p2[i][0]);
    for (int k = 1; k < 20; ++k) for (int i = 0; i < N; ++i) {
        if (p1[i][k-1] == -1) p1[i][k] = -1;
        else p1[i][k] = p1[p1[i][k-1]][k-1];
        if (p2[i][k-1] == -1) p2[i][k] = -1;
        else p2[i][k] = p2[p2[i][k-1]][k-1];
        if (p3[i][k-1] == -1) p3[i][k] = -1;
        else p3[i][k] = p3[p3[i][k-1]][k-1];
        if (p4[i][k-1] == -1) p4[i][k] = -1;
        else p4[i][k] = p4[p4[i][k-1]][k-1];
    }
}

int minimum_jumps(int A, int B, int C, int D) {
    int x = C;
    for (int k = 19; k >= 0; --k) if (p3[x][k] != -1 && p3[x][k] > B) x = p3[x][k];
    x = p3[x][0];
    if (x >= A && x <= B && p4[x][0] >= C && p4[x][0] <= D) return 1;
    int y = B;
    for (int k = 19; k >= 0; --k) if (p4[y][k] != -1 && p4[y][k] < C) y = p4[y][k];
    y = p4[y][0];
    if (y < C || y > D) return -1;
    x = B;
    for (int k = 19; k >= 0; --k) if (p3[x][k] != -1 && X[p3[x][k]] <= X[y] && p3[x][k] >= A) x = p3[x][k];
    int ans = 0;
    for (int k = 19; k >= 0; --k) if (p1[x][k] != -1 && X[p1[x][k]] <= X[y]) ans += (1<<k), x = p1[x][k];
    int ans1 = 0, ans2 = 1, x1 = x, x2 = p1[x][0];
    for (int k = 19; k >= 0; --k) if (p2[x1][k] != -1 && X[p2[x1][k]] <= X[y]) ans1 += (1<<k), x1 = p2[x1][k];
    for (int k = 19; k >= 0; --k) if (p4[x2][k] != -1 && p4[x2][k] < C) ans2 += (1<<k), x2 = p4[x2][k];
    ans2++, x2 = p4[x2][0];
    if ((x1 < C || x1 > D) && (x2 < C || x2 > D)) return -1;
    else if (x1 < C || x1 > D) return ans+ans2;
    else if (x2 < C || x2 > D) return ans+ans1;
    else return ans+min(ans1,ans2);
}

• 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