Submission #760321

#	Time	Username	Problem	Language	Result	Execution time	Memory
760321		danikoynov	Rainforest Jumps (APIO21_jumps)	C++14	37 / 100	4021 ms	21448 KiB

jumps

#include "jumps.h"

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

const int maxn = 2e5 + 10, maxlog = 21;
int n, h[maxn], left_child[maxn], right_child[maxn];
int dp[maxlog][maxn];
bool sorted;
void init(int N, vector<int> H)
{
    n = N;
    for (int i = 0; i < N; i ++)
    {
        left_child[i + 1] = right_child[i + 1] = 0;
        h[i + 1] = H[i];
    }
    sorted = true;
    for (int i = 1; i <= N; i ++)
        if (h[i] < h[i - 1])
        sorted = false;

    stack < int > st;
    for (int i = 1; i <= n; i ++)
    {
        while(!st.empty() && h[i] > h[st.top()])
            st.pop();
        if (!st.empty())
            left_child[i] = st.top();
        st.push(i);
    }

    while(!st.empty())
        st.pop();

    for (int i = n; i > 0; i --)
    {
        while(!st.empty() && h[i] > h[st.top()])
            st.pop();
        if (!st.empty())
            right_child[i] = st.top();
        st.push(i);
    }

    h[0] = 1e9;
    for (int i = 1; i <= n; i ++)
    {
        if (h[left_child[i]] > h[right_child[i]])
        dp[0][i] = left_child[i];
        else
            dp[0][i] = right_child[i];
    }

    for (int j = 1; j < maxlog; j ++)
        for (int i = 1; i <= n; i ++)
        dp[j][i] = dp[j - 1][dp[j - 1][i]];
}


int used[maxn];

int minimum_jumps(int A, int B, int C, int D)
{
    if (sorted)
        return C - B;
    A ++;
    B ++;
    C ++;
    D ++;
    /**if (A == B && C == D)
    {

        int ver = A, ans = 0;
        for (int bit = maxlog - 1; bit >= 0; bit --)
        {
            if (h[dp[bit][ver]] < h[C])
            {
                ans = ans + (1 << bit);
                ver = dp[bit][ver];
            }
        }
        if (left_child[ver] != C && right_child[ver] != C)
            return -1;
        return ans + 1;
    }*/
    int ans = 1e9;

    for (int i = 1; i <= n; i ++)
        used[i] = 0;

    queue < int > q;
    for (int i = A; i <= B; i ++)
    {
        q.push(i);
        used[i] = 1;
    }
//cout << "------------" << endl;
    while(!q.empty())
    {
        int cur = q.front();
        q.pop();
        ///cout << cur << endl;
        if (left_child[cur] != 0 && used[left_child[cur]] == 0)
        {
            used[left_child[cur]] = used[cur] + 1;
            q.push(left_child[cur]);
        }
        if (right_child[cur] != 0 && used[right_child[cur]] == 0)
        {
            used[right_child[cur]] = used[cur] + 1;
            q.push(right_child[cur]);
        }
    }

    for (int to = C; to <= D; to ++)
    {
        ///cout << "here "<< to << " " << used[to] << endl;
        if (used[to] != 0)
        {
            ans = min(ans, used[to] - 1);
        }
    }

    if (ans == 1e9)
        return -1;
    return ans;
}

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