Submission #553945

#	Time	Username	Problem	Language	Result	Execution time	Memory
553945		Jarif_Rahman	Rainforest Jumps (APIO21_jumps)	C++17	100 / 100	1248 ms	74784 KiB

jumps

#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;

struct sparse_table{
    vector<int> lg;
    vector<vector<pair<int, int>>> v;
    sparse_table(vector<int> _v){
        int n = _v.size();
        lg.resize(n+1);
        for(int i = 0; i <= n; i++) lg[i] = log2(i);
        int k = 0, p = 1;
        while(p < n) p*=2, k++;
        k++;
        v = vector<vector<pair<int, int>>>(n, vector<pair<int, int>>(k, make_pair(0, 0)));
        for(int i = 0; i < n; i++) v[i][0] = {_v[i], i};
        for(int p = 1; p < k; p++){
            for(int i = 0; i < n; i++){
                v[i][p] = max(v[i][p], v[i][p-1]);
                if(i + (1<<(p-1)) < n) v[i][p] = max(v[i][p], v[i + (1<<(p-1))][p-1]);
            }
        }
    }
    pair<int, int> query(int a, int b){
        int p = lg[b-a+1];
        return max(v[a][p], v[b-(1<<p)+1][p]);
    }
};

const int K = 21;
const int inf = 1e9;

int n;
vector<int> h;
vector<int> jump[2];
vector<int> anc[2][K];

sparse_table sp({});

template<int k>
int get_anc(int nd, int h){
    for(int i = 0; i < K; i++){
        if(h%2 == 1) nd = anc[k][i][nd];
        h/=2;
    }
    return nd;
}

template<int k>
int binlift(int nd, int l){
    if(h[nd] >= l) return 0;
    for(int i = K-1; i >= 0; i--) if(h[anc[k][i][nd]] <= l)
        return binlift<k>(anc[k][i][nd], l)+(1<<i);
    return 0;
}

void init(int N, vector<int> H){
    for(int &x: H) x--;
    n = N, h = H;
    h.pb(n);
    fill(jump, jump+2, vector<int>(n, n));
    fill(anc[0], anc[0]+K, vector<int>(n+1, n));
    fill(anc[1], anc[1]+K, vector<int>(n+1, n));

    sp = sparse_table(H);

    stack<int> st;
    for(int i = n-1; i >= 0; i--){
        while(!st.empty() && h[i] > h[st.top()]){
            jump[0][st.top()] = i;
            st.pop();
        }
        st.push(i);
    }
    while(!st.empty()) st.pop();

    for(int i = 0; i < n; i++){
        while(!st.empty() && h[i] > h[st.top()]){
            jump[1][st.top()] = i;
            st.pop();
        }
        st.push(i);
    }
    while(!st.empty()) st.pop();

    for(int i = 0; i < n; i++){
        anc[0][0][i] = h[jump[0][i]] < h[jump[1][i]] ? jump[0][i] : jump[1][i];
        anc[1][0][i] = h[jump[0][i]] > h[jump[1][i]] ? jump[0][i] : jump[1][i];
        if(anc[1][0][i] == n) anc[1][0][i] = anc[0][0][i];
    }

    for(int p = 1; p < K; p++) for(int i = 0; i <= n; i++)
        anc[0][p][i] = anc[0][p-1][anc[0][p-1][i]],
        anc[1][p][i] = anc[1][p-1][anc[1][p-1][i]];
}

int minimum_jumps(int A, int B, int C, int D){
    int l = 1, r = B-A+1;
    int m1 = 0, m2 = sp.query(C, D).f;
    if(B+1 < C) m1 = sp.query(B+1, C-1).f;

    if(m1 > m2) return -1;

    while(l < r){
        int md = (l+r)/2;
        if(sp.query(B-md+1, B).f > m2) r = md;
        else l = md+1;
    }
    int S = A;
    if(sp.query(B-l+1, B).f > m2){
        S = B-l+2;
        if(S > B) return -1;
    }
    S = sp.query(S, B).sc;
    
    int ans = binlift<1>(S, m1);
    int nd = get_anc<1>(S, ans);
    if(h[nd] >= m1 && h[nd] <= m2) return ans+1;
    if(h[anc[1][0][nd]] <= m2) return ans+2;

    int x = binlift<0>(nd, m1);
    nd = get_anc<0>(nd, x);
    ans+=x;

    if(h[nd] >= m1 && h[nd] <= m2) return ans+1;
    if(h[anc[1][0][nd]] <= m2) return ans+2;

    return -1;
}

• 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