Submission #744963

#	Time	Username	Problem	Language	Result	Execution time	Memory
744963		RushB	Rainforest Jumps (APIO21_jumps)	C++17	44 / 100	1162 ms	35752 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a); i < (b); i++) 
using namespace std;
const int N = 2e5 + 5;
const int L = 18;
int prv[N], nxt[N], n, h[N], sparse[N][L], mx[4 * N];
vector<int> H;

int argmax(int x, int y) {
	return H[x] > H[y] ? x : y;
}

void build_tree(int v, int l, int r) {
	if (l + 1 == r) {
		mx[v] = l;
		return;
	}
	int m = l + r >> 1;
	build_tree(v << 1, l, m), build_tree(v << 1 | 1, m, r);
	mx[v] = argmax(mx[v << 1], mx[v << 1 | 1]);
}
int get_mx(int v, int l, int r, int L, int R) {
	if (R <= l || r <= L || R <= L) return n;
	if (L <= l && r <= R) return mx[v];
	int m = l + r >> 1;
	return argmax(get_mx(v << 1, l, m, L, R), get_mx(v << 1 | 1, m, r, L, R));
}

void init(int _n, std::vector<int> _H) {
	n = _n;
	H.swap(_H);	
	build_tree(1, 0, n);
	H.push_back(-1);

	vector<int> st;
	FOR(i, 0, n) {
		while (st.size() && H[st.back()] <= H[i]) st.pop_back();
		prv[i] = (st.empty() ? -1 : st.back());
		st.push_back(i);
	}
	st.clear();
	for (int i = n - 1; i >= 0; i--) {
		while (st.size() && H[st.back()] <= H[i]) st.pop_back();
		nxt[i] = (st.empty() ? n : st.back());
		st.push_back(i);
	}
	for (int i = n - 1; i >= 0; i--) h[i] = h[nxt[i]] + 1;
	
	for (int i = 0; i < n; i++) {
		int x = (prv[i] == -1 ? -1 : H[prv[i]]), y = (nxt[i] == n ? -1 : H[nxt[i]]);
		if (y == -1 && x == -1) sparse[i][0] = i;
		else sparse[i][0] = (x > y ? prv[i] : nxt[i]);
	}
		
	FOR(j, 1, L) FOR(i, 0, n) sparse[i][j] = sparse[sparse[i][j - 1]][j - 1];

}

int minimum_jumps(int A, int B, int C, int D) {
	assert(C == D);
	int x = get_mx(1, 0, n, max(A, prv[C] + 1), B + 1);
	if (x == n || prv[C] >= x) return -1;

	int t = 0;
	for (int i = L - 1; i >= 0; i--) if (H[sparse[x][i]] < H[C]) {
		x = sparse[x][i];
		t |= 1 << i;
	}
	return t + h[x] - h[C];
}

Compilation message (stderr)

jumps.cpp: In function 'void build_tree(int, int, int)':
jumps.cpp:19:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   19 |  int m = l + r >> 1;
      |          ~~^~~
jumps.cpp: In function 'int get_mx(int, int, int, int, int)':
jumps.cpp:26:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   26 |  int m = l + r >> 1;
      |          ~~^~~

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