Submission #570392

#	Time	Username	Problem	Language	Result	Execution time	Memory
570392		grt	Rainforest Jumps (APIO21_jumps)	C++17	21 / 100	1060 ms	51524 KiB

jumps

#include <bits/stdc++.h>
#define PB push_back
#define ST first
#define ND second

//#pragma GCC optimize ("O3")
//#pragma GCC target("tune=native")

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
//typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

using namespace std;
using ll = long long;
using pi = pair<int, int>;
using vi = vector<int>;

const int nax = 200 * 1000 + 10, INF = 1e9 + 10;
int n;
int h[nax];
int lft[nax], rght[nax];
int par[nax][19];
int par2[nax][19];
int mx[nax][19];
int T[(1 << 18)], R;
int inv[nax];

int qr(int a, int b) {
	a += R, b += R;
	int w = max(T[a], T[b]);
	while(a/2 != b/2) {
		if(a % 2 == 0) w = max(w, T[a + 1]);
		if(b % 2 == 1) w = max(w, T[b - 1]);
		a >>= 1;
		b >>= 1;
	}
	return w;
}

int get_pos(int a, int H) {
	int v = a + R;
	if(T[v] >= H) return a;
	while(v > 1) {
		if(v % 2 == 1) {
			if(T[v ^ 1] >= H) {
				v ^= 1;
				break;
			}
		}
		v >>= 1;
	}
	if(v == 1) return -1;
	while(v < R) {
		if(T[v << 1 | 1] >= H) {
			v = v << 1 | 1;
		} else {
			v = v << 1;
		}
	}
	return v - R;
}

void init(int N, vi H) {
	n = N;
	R = 1;
	while(R <= n) R <<= 1;
	for(int i = 0; i < n; ++i) {
		h[i + 1] = H[i];
		inv[H[i]] = i + 1;
	}
	for(int i = 1; i <= n; ++i) {
		T[i + R] = h[i];
	}
	for(int i = R - 1; i >= 1; --i) {
		T[i] = max(T[i << 1], T[i << 1 | 1]);
	}
	h[0] = INF + 1, h[n + 1] = INF;
	vi S = {0};
	for(int i = 1; i <= n; ++i) {
		while(h[S.back()] < h[i]) S.pop_back();
		lft[i] = S.back();
		S.PB(i);
	}
	S = {n + 1};
	for(int i = n; i >= 1; --i) {
		while(h[S.back()] < h[i]) S.pop_back();
		rght[i] = S.back();
		S.PB(i);
	}
	for(int i = 1; i <= n; ++i) {
		if(h[lft[i]] > h[rght[i]]) {
			par[i][0] = lft[i];
			par2[i][0] = rght[i];
		} else {
			par[i][0] = rght[i];
			par2[i][0] = lft[i];
		}
		mx[i][0] = max(lft[i], rght[i]);
	}
	par[n + 1][0] = 0;
	par2[n + 1][0] = 0;
	for(int j = 1; j < 19; ++j) {
		for(int i = 1; i <= n + 1; ++i) {
			par[i][j] = par[par[i][j - 1]][j - 1];
			par2[i][j] = par2[par2[i][j - 1]][j - 1];
			mx[i][j] = max(mx[i][j - 1], mx[par[i][j - 1]][j - 1]);
		}
	}
}

int minimum_jumps(int a, int b, int c, int d) {
	a++, b++, c++, d++;
	int H = qr(c, d);
	//for(int i = c; i <= d; ++i) {
		//H = max(H, h[i]);
	//}
	//int forb = get_pos(b, H);
	//a = max(a, forb + 1);
	//if(a > b) {
		//return -1;
	//}
	//int p = inv[qr(a, b)];
	int p = b;
	for(int i = b - 1; i >= a; --i) {
		if(h[i] > H) break;
		if(h[p] < h[i]) p = i;
	}
	int ans = 0;
	for(int i = 18; i >= 0; --i) {
		if(h[par[p][i]] <= H && mx[p][i] < c) {
			p = par[p][i];
			ans += (1 << i);
		}	
	}
	if(mx[p][0] >= c) {
		ans++;
		p = mx[p][0];
	} else {
		for(int i = 18; i >= 0; --i) {
			if(h[par2[p][i]] <= H && par2[p][i] < c) {
				p = par2[p][i];
				ans += (1 << i);
			}
		}
		p = par2[p][0];
		ans++;
	}
	if(p < c || p > d) return -1;
	return ans;
	
}


//int main() {
	//ios_base::sync_with_stdio(0);
	//cin.tie(0);
	//init(7, {3, 2, 1, 6, 4, 5, 7});
	//cout << minimum_jumps(4, 4, 6, 6) << "\n";
	//cout << minimum_jumps(1, 3, 5, 6) << "\n";
	//cout << minimum_jumps(0, 1, 2, 2) << "\n";
//}

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