Submission #941981

#	Time	Username	Problem	Language	Result	Execution time	Memory
941981		beaboss	Ancient Books (IOI17_books)	C++14	0 / 100	2044 ms	600 KiB

books

// Source: https://oj.uz/problem/view/IOI17_books
// 
#include "books.h"


#include "bits/stdc++.h"

using namespace std;

#define s second
#define f first
#define pb push_back

typedef long long ll;

typedef pair<int, int> pii;
typedef vector<pii> vpii;

typedef vector<int> vi;

#define FOR(i, a, b) for (int i = (a); i<b; i++)

bool ckmin(int& a, int b){ return b < a ? a = b, true : false; }

bool ckmax(int& a, int b){ return b > a ? a = b, true : false; }

const int N = 1e6 + 10;
int ri[N], le[N];
bool vis[N];
vi nxt;
int n;
int l,r ;

void extend() {
	int ll = nxt[l];
	while (ll < l && l > 0) {
		l--;
		ll = min(ll, nxt[l]);
	}
	int rr = nxt[r];
	while (r < rr && r < n-1) {
		r++;
		rr = max(rr, nxt[r]);
	}
}

ll minimum_walk(vector<int> p, int s) {
	n = p.size();
	l = r = s;
	nxt = p;
	int ans = 0;
	FOR(i, 0, n) ans += abs(i - p[i]);

	int st = 0;
	for (;st < n;st++) if (p[st] != st) break;
	int en = n-1;
	for (;en >= 0;en--) if (p[en] != en) break;
	
	if (st >= en) return 0;

	while (l > st || r < en) {
		extend();

		int lo = l;
		int ro = r;

		int cr = 0;
		while (nxt[r] >= l && r != en) {
			cr+=2;r++;extend();
		}
		bool rw = (nxt[r] < l);

		swap(l, lo);swap(r, ro);

		int cl = 0;
		while (nxt[l] <= r && l != st) {
			cl+=2;l++;extend();
		}

		bool lw = (nxt[l] > r);

		l = min(l, lo);
		r = max(r, ro);

		assert(lw ^ rw);
		if (!lw && !rw) {
			ans += cl + cr;
			break;
		}
		ans += min(cl, cr);
	}

	return ans;

}



// int main() {
// 	ios::sync_with_stdio(false);
// 	cin.tie(nullptr);

// 	// FOR(i, 0, 8) {
// 	// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// 	// int n = 100;
// 	// vi here(n);
// 	// FOR(i, 0, n) here[i] = i;
// 	// shuffle(here.begin(), here.end(), rng);
// 	// FOR(i, 0, n) cout << here[i] << ' ';
// 	// cout << endl;


// 	int res = minimum_walk({0, 2, 3, 1}, 2);
// 	cout << res << endl;

// }

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