Submission #69528

#	Time	Username	Problem	Language	Result	Execution time	Memory
69528		Noam527	Ancient Books (IOI17_books)	C++17	50 / 100	268 ms	20220 KiB

books

#include "books.h"
#include <bits/stdc++.h>
#define endl '\n'
#define fast ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define debug cout << "ok" << endl
#define finish(x) return cout << x << endl, 0
typedef long long ll;
typedef long double ldb;
const int md = 1e9 + 7, inf = 1e9 + 7;
const ll hs = 199;
const ldb eps = 1e-9, pi = acos(-1);
using namespace std;

int n;
vector<int> a, vis, to;

int cycle(int st) {
	vis[st] = 1;
	int rtn = st;
	st = a[st];
	while (!vis[st]) {
		rtn = max(rtn, st);
		vis[st] = 1;
		st = a[st];
	}
	return rtn;
}

ll minimum_walk(vector<int> p, int s) {
	n = p.size();
	a = p;
	ll sum = 0;
	for (int i = 0; i < n; i++)
		sum += abs(i - a[i]);

	int l = 0, r = n - 1;
	while (l < n && a[l] == l) l++;
	if (l == n) return 0;
	while (a[r] == r) r--;



	vis.resize(n, 0);
	to.resize(n, -1);
	for (int i = l; i <= r; i++)
		if (!vis[i])
			to[i] = cycle(i);
	ll cnt = 0, mxpos = 0;
	for (int i = l; i <= r; i++)
		if (to[i] != -1) {
			if (i < mxpos) mxpos = max(mxpos, (ll)to[i]);
			else mxpos = to[i], cnt++;
		}
	ll rtn = sum + 2LL * (cnt - 1);
	if (s < l) rtn += 2 * (l - s);
	if (r < s) rtn += 2 * (s - r);
	return rtn;
}

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