Submission #566559

#	Time	Username	Problem	Language	Result	Execution time	Memory
566559		Temmie	Ancient Books (IOI17_books)	C++17	50 / 100	498 ms	70840 KiB

books

//#include "public_c/public/cpp/books.h"
#include "books.h"

#include <bits/stdc++.h>

long long minimum_walk(std::vector <int> p, int s) {
	int n = p.size();
	std::vector <int> min(n, 1 << 30);
	std::vector <int> max(n, -1);
	std::vector <int> col(n, -1);
	for (int i = 0, cnt = 0; i < n; i++) {
		if (col[i] != -1) {
			continue;
		}
		int u = i;
		do {
			min[cnt] = std::min(min[cnt], u);
			max[cnt] = std::max(max[cnt], u);
			col[u] = cnt;
			u = p[u];
		} while (u != i);
		cnt++;
	}
	int l = 0, r = n - 1;
	while (l < s && l == p[l]) {
		l++;
	}
	while (r > s && r == p[r]) {
		r--;
	}
	std::set <int> st;
	for (int i = l; i <= r; i++) {
		st.insert(i);
	}
	int dr = 0;
	std::vector <int> dis(n, 1 << 30);
	std::deque <std::pair <int, int>> q;
	q.emplace_back(col[s], dis[col[s]] = 0);
	while (q.size()) {
		int v = q.front().first;
		int d = q.front().second;
		q.pop_front();
		if (d != dis[v]) {
			continue;
		}
		int mn = min[v];
		int mx = max[v];
		dr += v != col[s] && s >= mn && s <= mx;
		while (true) {
			int u;
			auto it = st.lower_bound(mn);
			if (it == st.end() || (u = *it) > mx) {
				break;
			}
			st.erase(it);
			if (d < dis[col[u]]) {
				q.emplace_front(col[u], dis[col[u]] = d);
			}
		}
		if (v < r && d + 1 < dis[col[v + 1]]) {
			q.emplace_back(col[v + 1], dis[col[v + 1]] = d + 1);
		}
		if (v > l && d + 1 < dis[col[v - 1]]) {
			q.emplace_back(col[v - 1], dis[col[v - 1]] = d + 1);
		}
	}
	long long ans = 0;
	for (int i = l; i <= r; i++) {
		ans += abs(i - p[i]);
	}
	int cnt = 0;
	for (int i = l; i <= r; i++) {
		dr += !cnt && s < i;
		cnt += max[col[i]] == i;
		cnt -= min[col[i]] == i;
	}
	cnt = 0;
	for (int i = r; i >= l; i--) {
		dr += !cnt && s > i;
		cnt -= max[col[i]] == i;
		cnt += min[col[i]] == i;
	}
	return ans + dr * 2;
}

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 28 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30