Submission #831220

#	Time	Username	Problem	Language	Result	Execution time	Memory
831220		NK_	Towers (NOI22_towers)	C++17	100 / 100	1450 ms	133816 KiB

Main

// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>

using namespace std;
 
#define nl '\n'
#define pb push_back
#define pf push_front

#define mp make_pair
#define f first
#define s second
#define sz(x) int(x.size())
 
template<class T> using V = vector<T>;
using pi = pair<int, int>;
using vi = V<int>;
using vpi = V<pi>;

using ll = long long;
using pl = pair<ll, ll>;
using vpl = V<pl>;
using vl = V<ll>;

using db = long double;

template<class T> using pq = priority_queue<T, V<T>, greater<T>>;

const int MOD = 1e9 + 7;
const ll INFL = ll(1e16) + 10;

int main() {
	cin.tie(0)->sync_with_stdio(0);
	
	int N; cin >> N;
	vpi A(N); for(auto& x : A) {
		cin >> x.f >> x.s;
	}

	int ROWS = 0, COLS = 0;
	for(int t = 0; t < 2; t++) {
		vi X; for(auto& x : A) X.pb(x.f); 

		sort(begin(X), end(X)); 
		// X.erase(unique(begin(X), end(X)), end(X));

		for(auto& x : A) {
			x.f = lower_bound(begin(X), end(X), x.f) - begin(X);
			swap(x.f, x.s);
		}

		ROWS = sz(X); swap(ROWS, COLS);
	}

	unordered_map<ll, int> IDX; for(int i = 0; i < N; i++) {
		IDX[A[i].f * 1LL * COLS + A[i].s] = i;
	}

	V<vi> C(COLS);
	for(int i = 0; i < N; i++) C[A[i].s].pb(A[i].f);
	for(int i = 0; i < COLS; i++) sort(begin(C[i]), end(C[i]));

	const pi EMP = mp(-1, -1);
	vpi RF(ROWS, EMP); 
	vpi RB(ROWS, EMP); 


	vi POS(2 * COLS, -1); int Q = 0;
	vi stk;
	function<void(int)> update = [&](int X) {
		stk.pb(X);

		while(sz(stk)) {

			int x = stk.back(); stk.pop_back(); 
			if (POS[x] == -1) continue;

			// 2*y+c => y is col # and c is dir (0 - dwn (+1), 1 - up (-1));
			int y = x / 2, dir = (x % 2 ? -1 : +1);
			while(1) {
				Q++; assert(Q <= 5 * N);

				if (POS[x] < 0 || POS[x] >= sz(C[y])) {
					POS[x] = -1; break;
				}

				if (POS[2*y] == POS[2*y+1]) {
					POS[x] = -1;
					break; // stop because same as other one
				}

				int r = C[y][POS[x]]; // row

				// check if you can put it in
				if (RB[r] == EMP || RB[r].f < y) { // sz(R[r]) == 2 put in at the back
					if (RB[r] != EMP) {
						int i = RB[r].s;
						RB[r] = mp(y, x);
						stk.pb(i); 
					} else RB[r] = mp(y, x);
					break;
				} 

				if (RF[r] == EMP || y < RF[r].f) { // sz(R[r]) == 2 put in at the front
					if (RF[r] != EMP) {
						int i = RF[r].s;
						RF[r] = mp(y, x);
						stk.pb(i);
					} else RF[r] = mp(y, x);
					break;
				}

				POS[x] += dir;
			}
		}
	};


	for(int c = 0; c < COLS; c++) {
		POS[2 * c] = 0; 
		update(2 * c); 

		POS[2 * c + 1] = sz(C[c]) - 1;
		update(2 * c + 1);
	}

	vpi take;
	for(int i = 0; i < 2 * COLS; i++) {
		int c = i / 2; 
		if (0 <= POS[i] && POS[i] < sz(C[c])) {
			take.pb(mp(C[c][POS[i]], c));
		}
	}

	string ans(N, '0');
	for(auto& p : take) {
		ans[IDX[p.f * 1LL * COLS + p.s]] = '1';
	}

	cout << ans << nl;

	// cerr << Q << endl;


    return 0;
} 	

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 7 / 7
• Subtask 4: 6 / 6
• Subtask 5: 31 / 31
• Subtask 6: 21 / 21
• Subtask 7: 19 / 19