Submission #430521

#	Time	Username	Problem	Language	Result	Execution time	Memory
430521		Sorting	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	4016 ms	36276 KiB

jumps

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

using namespace std;

const int N = 2e5 + 3;
const int LOGN = 20;

int n, h[N];
int right_nxt[LOGN][N], big_nxt[LOGN][N];
int r[N], l[N];

void build_l_r(){
    stack<int> st;

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

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

bool valid(int pos){
    return pos >= 0 && pos < n;
}

void init(int _n, vector<int> _h){
    n = _n;
    for(int i = 0; i < n; ++i)
        h[i] = _h[i];

    build_l_r();
    for(int i = 0; i < n; ++i)
        right_nxt[0][i] = r[i];
    for(int i = 0; i < n; ++i){
        if(l[i] == -1 || r[i] == n){
            big_nxt[0][i] = (l[i] == -1) ? l[i] : r[i];
        }
        else{
            big_nxt[0][i] = (h[l[i]] > h[r[i]]) ? l[i] : r[i];
        }
    }

    for(int j = 1; j < LOGN; ++j){
        for(int i = 0; i < n; ++i){
            if(!valid(big_nxt[j - 1][i])) big_nxt[j][i] = big_nxt[j - 1][i];
            else big_nxt[j][i] = big_nxt[j - 1][big_nxt[j - 1][i]];
            
            if(!valid(right_nxt[j - 1][i])) right_nxt[j][i] = right_nxt[j - 1][i];
            else right_nxt[j][i] = right_nxt[j - 1][right_nxt[j - 1][i]];
        }
    }
}

int minimum_jumps(int a, int b, int c, int d){
    int mx2 = 0;
    for(int i = c; i <= d; ++i)
        mx2 = max(mx2, h[i]);

    int mx_mid = 0;
    for(int i = b + 1; i <= c - 1; ++i)
        if(h[i] > mx_mid)
            mx_mid = h[i];
    if(mx_mid > mx2) return -1; 

    int mx1 = 0, idx = -1;
    for(int i = b; i >= a; --i){
        if(h[i] > mx2) break;
        if(h[i] > mx1){
            mx1 = h[i];
            idx = i;
        }
    }

    if(!mx1) return -1;

    int ans = 0;
    for(int i = LOGN - 1; i >= 0; --i){
        if(valid(big_nxt[i][idx]) && h[big_nxt[i][idx]] <= mx_mid){
            ans += 1 << i;
            idx = big_nxt[i][idx];
        }
    }
    if(valid(big_nxt[0][idx]) && right_nxt[0][idx] < c){
        ++ans;
        idx = big_nxt[0][idx];
    }
    for(int i = LOGN - 1; i >= 0; --i){
        if(valid(right_nxt[i][idx]) && right_nxt[i][idx] < c){
            ans += 1 << i;
            idx = right_nxt[i][idx];
        }
    }
    return ans + 1;
}

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