Submission #977897

#	Time	Username	Problem	Language	Result	Execution time	Memory
977897		rshohruh	Rainforest Jumps (APIO21_jumps)	C++14	44 / 100	4103 ms	53080 KiB

jumps

#include "jumps.h"

#include <vector>
#include <bits/stdc++.h>
using namespace std;
int inf = 1e9;
int n, l;
vector<int> h;
vector<pair<int, int>> a;
vector<vector<int>> up, A;
void init(int N, std::vector<int> H)
{
	n = N+1;
	h = H;
	l = ceil(log2(n));

	h.push_back(n);
	a.resize(n);
	up.resize(n, vector<int>(l+1));
	A.resize(n, vector<int>(l+1));

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

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

	vector<int> inv_h(n+1);
	for(int i = 0; i < n; ++i) inv_h[h[i]] = i;
	for(int i = n; i > 0; --i){
		int id = inv_h[i];

		if(h[a[id].first] > h[a[id].second]) up[id][0] = a[id].first;
		else up[id][0] = a[id].second;
		
		A[id][0] = a[id].second;

		// cerr << id << ' ' << up[id][0] << ' ';
		for(int j = 1; j <= l; ++j){
			up[id][j] = up[up[id][j-1]][j-1];
			A[id][j] = A[A[id][j-1]][j-1];
			// cerr << up[id][j] << ' ';
		}
		// cerr << endl;
		// cout << a[id].first << ' ' << id << ' ' << a[id].second << endl;
	}

}

int ans(int L, int R){
	int ans = 0;
	for(int i = l; i >= 0; --i){
		if(h[up[L][i]] <= h[R]){
			L = up[L][i];
			ans += (1<<i);
		}
	}
	for(int i = l; i >= 0; --i){
		if(h[A[L][i]] <= h[R]){
			L = A[L][i];
			ans += (1<<i);
		}
	}
	if(L == R) return ans;
	return inf;
}

int minimum_jumps(int A, int B, int C, int D)
{
	// return 0;
	int res = inf;
	for(int id = C; id <= D; ++id){
		int mx = 0, mx_id = B;
		for(int i = B; i >= A; --i){
			if(h[i] > h[id]) break;
			if(h[i] > mx){
				mx = h[i];
				mx_id = i;
			}
		}
		res = min(res, ans(mx_id, id));
	}
	return (res == inf ? -1 : res);
}

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