Submission #440650

#	Time	Username	Problem	Language	Result	Execution time	Memory
440650		Elegia	Rainforest Jumps (APIO21_jumps)	C++17	100 / 100	1261 ms	46456 KiB

jumps

#include "jumps.h"

const int MAX_N = 200010, L = 18;

int N;
int h[MAX_N], left[MAX_N][L], right[MAX_N][L], gr[MAX_N][L];

void init(int _N, std::vector<int> _H) {
	N = _N;
	std::copy(_H.begin(), _H.end(), h + 1);
	static int stack[MAX_N], ord[MAX_N];
	int cnt = 0;
	for (int i = 1; i <= N; ++i) {
		while (cnt && h[i] > h[stack[cnt]])
			right[stack[cnt--]][0] = i;
		left[i][0] = stack[cnt];
		stack[++cnt] = i;
	}
	for (int i = 1; i <= N; ++i) for (int j = 1; j != L; ++j)
		left[i][j] = left[left[i][j - 1]][j - 1];
	std::fill(right[N + 1], right[N + 1] + L, N + 1);
	for (int i = N; i; --i) {
		if (!right[i][0]) right[i][0] = N + 1;
		for (int j = 1; j != L; ++j)
			right[i][j] = right[right[i][j - 1]][j - 1];
	}
	for (int i = 1; i <= N; ++i) ord[h[i]] = i;
	std::fill(gr[N + 1], gr[N + 1] + L, N + 1);
	for (int i = N; i; --i) {
		int j = ord[i];
		gr[j][0] = (h[left[j][0]] > h[right[j][0]] ? left : right)[j][0];
		for (int k = 1; k != L; ++k) gr[j][k] = gr[gr[j][k - 1]][k - 1];
	}
}

int minimum_jumps(int A, int B, int C, int D) {
	++A; ++B; ++C; ++D;
	for (int i = L - 1; i >= 0; --i) if (left[D][i] >= C)
		D = left[D][i];
	for (int i = L - 1; i >= 0; --i) if (left[B][i] >= A && h[left[B][i]] < h[D])
		B = left[B][i];
	int X = B;
	for (int i = L - 1; i >= 0; --i) if (right[X][i] < C)
		X = right[X][i];
	int ret = 1;
	for (int i = L - 1; i >= 0; --i) if (gr[B][i] <= N && h[gr[B][i]] <= h[X]) {
		ret += 1 << i;
		B = gr[B][i];
	}
	if (right[B][0] >= C && right[B][0] <= D) return ret;
	if (gr[B][0] <= N && h[gr[B][0]] <= h[D]) {
		++ret;
		B = gr[B][0];
	}
	for (int i = L - 1; i >= 0; --i) if (right[B][i] < C) {
		ret += 1 << i;
		B = right[B][i];
	}
	if (h[B] > h[D]) return -1;
	return ret;
}

• 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