Submission #1119336

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119336		vako_p	Rainforest Jumps (APIO21_jumps)	C++14	100 / 100	2321 ms	125772 KiB

jumps

#include <bits/stdc++.h>
#include "jumps.h"
using namespace std;
#define ll long long
#define pb push_back
 
const int mxN = 3e5 + 5;
ll n,a[mxN],p[mxN][25],p1[mxN][25],p2[mxN][25],L[mxN],R[mxN];
stack<ll> st;

void init(int N, vector<int> H){
	n = N;
	for(int i = 1; i <= n; i++) a[i] = H[i - 1];
	
	a[0] = a[n + 1] = 1e9;
	st.push(0);
	for(int i = 1; i <= n; i++){
		while(!st.empty()){
			if(a[st.top()] < a[i]) st.pop();
			else break;
		}
		L[i] = st.top();
		st.push(i);
	}	
	while(!st.empty()) st.pop();
	st.push(n + 1);
	for(int i = n; i > 0; i--){
		while(!st.empty()){
			if(a[st.top()] < a[i]) st.pop();
			else break;
		}
		R[i] = st.top();
		st.push(i);
	}
	
	for(int i = 0; i <= 20; i++) p[n + 1][i] = p1[n + 1][i] = p2[n + 1][i] = n + 1;
	for(int i = n; i > 0; i--){
		p[i][0] = R[i];
		for(int j = 1; j <= 20; j++) p[i][j] = p[p[i][j - 1]][j - 1];
	}
	for(int i = 1; i <= n; i++){
		p2[i][0] = L[i];
		for(int j = 1; j <= 20; j++) p2[i][j] = p2[p2[i][j - 1]][j - 1];
	}
	for(int j = 0; j <= 20; j++){
		for(int i = 1; i <= n; i++){
			if(j == 0){
				if(a[R[i]] > a[L[i]]) p1[i][j] = R[i];
				else p1[i][j] = L[i];
				continue;
			}
			p1[i][j] = p1[p1[i][j - 1]][j - 1];
		}
	}
}

ll f(ll idx, ll num){
	ll ans = 0;
	for(int i = 20; i >= 0; i--){
		if(a[p[idx][i]] < num){
			idx = p[idx][i];
			ans += (1LL << i);
		} 
	}
	return ans;
}

int minimum_jumps(int A, int B, int C, int D){
	A++;B++;C++;D++;
	ll idx = B,num;
	for(int i = 20; i >= 0; i--) if(p[idx][i] < C) idx = p[idx][i];
	if(idx == B) num = 0;
	else num = a[idx];
	if(p[idx][0] > D) return -1;
	idx = B;
	bool ok = (a[idx] < num);
	for(int i = 20; i >= 0; i--){
		if(p2[idx][i] >= A){
			if(a[p2[idx][i]] >= num){
				ok = false;
				continue;
			}
			idx = p2[idx][i];
		}
	}
	ll ans = f(idx, num + 1) + 1;	
	if(ok){
		ll ans1 = 1;
		for(int i = 20; i >= 0; i--){
			if(a[p1[idx][i]] < num){
				ans1 += (1LL << i);
				idx = p1[idx][i];
			}
		}
		if(p1[idx][0] != 0 and p[p1[idx][0]][0] <= D) return min(ans, ans1 + 1LL); 
		return min(ans1 + f(idx, num + 1), ans);
	}
	if(p2[idx][0] != 0 and p[p2[idx][0]][0] <= D) return 1;
	return ans;
}

• 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