Submission #1205589

#	Time	Username	Problem	Language	Result	Execution time	Memory
1205589		countless	Ancient Books (IOI17_books)	C++20	50 / 100	90 ms	15296 KiB

books

#include "books.h"
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;

const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-12;

#define endl "\n"
#define sp <<" "<<
#define REP(i, a, b) for(ll i = a; i < b; i++)
#define dbg(x) cout << #x << " = " << x << endl
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fast_io() ios_base::sync_with_stdio(false); cin.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())

struct custom_hash {
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}

	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
};

template <typename Key, typename Value>
using hash_map = unordered_map<Key, Value, custom_hash>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// uniform_int_distribution<int>(a, b)(rng);
// shuffle(all(a), rng);

ll minimum_walk(vector<int> p, int s) {
	assert(s == 0);

	int n = p.size();
	int last = 0;
	ll ans = 0;

	vector<int> pos(n);
	REP(i, 0, n) {
		pos[p[i]] = i;
	}

	vector<bool> vis(n, false);
	vector<pair<pair<int, int>, int>> sub;
	auto touch = [&](int i) -> void {
		int ele = p[i], loc = i;

		// check overflow later
		ll curr = 2LL * loc;
		int l = n+1, r = -1;
		while (loc != ele and !vis[ele]) {
			curr += abs(loc - ele);
			vis[ele] = true;
			loc = ele, ele = p[loc];
			l = min(l, ele), r = max(r, ele);
		}

		sub.push_back({{l, r}, curr});
		ans += curr;
	};

	REP(i, 0, n) {
		if (!vis[i] and p[i] != i) {
			touch(i);
		}
	}

	sort(all(sub));
	// for (auto &x : sub) {
	// 	cerr << "(" << x.fi.fi << ", " << x.fi.se << " - " << x.se << "), ";
	// }	cerr << endl;

	for (auto &x : sub) {
		if (x.fi.fi <= last) {
			ans -= 2LL * x.fi.fi;
		} else {
			ans -= 2LL * last;
		}

		last = max(last, x.fi.se);
	}

	return ans;
}

// int main() {
// 	vector<int> wow = {0, 1, 2, 3};

// 	do {
// 		REP(i, 0, 4) cerr << wow[i] << " ";
// 		cerr << endl;
// 		cerr << minimum_walk(wow, 0) << endl;
// 	} while (next_permutation(all(wow)));

// 	return 0;
// }

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