Submission #833721

#	Time	Username	Problem	Language	Result	Execution time	Memory
833721		Josia	Ancient Books (IOI17_books)	C++17	50 / 100	168 ms	39344 KiB

books

#include "books.h"
#include <bits/stdc++.h>

using namespace std;

#define int int64_t


vector<int> p;
int s;
int n;
int res;

vector<int> cycles;
pair<int, int> getCycle(int v, int ind) {
	if (cycles[v] != -1) return {-1, -1};

	pair<int, int> range = {1e9, -1e9};

	while (cycles[v] == -1) {
		cycles[v] = ind;
		range.first = min(range.first, v);
		range.second = max(range.second, v);
		res += abs(p[v]-v);
		v = p[v];
	}

	return range;
}


long long minimum_walk(vector<signed> _p, signed _s) {
	s = _s;
	n = _p.size();
	p.resize(n); for (int i = 0; i<n; i++) p[i] = _p[i];

	cycles.assign(n, -1);
	res = 0;

	vector<pair<int, int>> ranges;
	for (int i = 0; i<n; i++) {
		ranges.push_back(getCycle(i, i));
		if (ranges.back().first == ranges.back().second) ranges.pop_back();
	}

	ranges.push_back({s, s});

	sort(ranges.begin(), ranges.end());


	set<int> active = {ranges[0].second};

	for (int i = 1; i<(int)ranges.size(); i++) {
		res += 2*max((int)0, ranges[i].first-*active.rbegin());
		active.insert(ranges[i].second);
	}


	return res;
}

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