Submission #925320

#	Time	Username	Problem	Language	Result	Execution time	Memory
925320		belgianbot	Palembang Bridges (APIO15_bridge)	C++14	100 / 100	69 ms	10196 KiB

bridge

#include <bits/stdc++.h>
#define int long long
#define sz(x) (long long)(x.size())

using namespace std;

struct traj{
	int l, r;
	long double mid;
};
vector <traj> a;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int K, N; cin >> K >> N;
	
	int ans(0);
	for (int i(0); i < N; i++) {
		char riv1, riv2;
		int pos1, pos2;
		cin >> riv1 >> pos1 >> riv2 >> pos2;
		
		if (pos2 < pos1) swap(pos1, pos2);
		if (riv1 != riv2) {
			ans++;
			a.push_back ({pos1, pos2, (long double)( (pos1 + pos2) / 2)});
		}
		else ans += pos2 - pos1;
	}
	if (sz(a) == 0){
		 cout << ans << '\n';
		 return 0;
	 }
	sort (a.begin(), a.end(), [](traj &A, traj &B){return A.mid < B.mid;});
	
	priority_queue <int> left;
	priority_queue <int, vector<int>, greater <int>> right;
	
	vector <int> score (sz(a)), score2 (sz(a));
	
	int median = a[0].l;
	left.push(a[0].l);
	right.push(a[0].r);
	score[0] = a[0].r - a[0].l;
	for (int i(1); i < sz(a); i++) {
		score[i] = score[i - 1] + abs(a[i].l - median) + abs(a[i].r - median);
		if (a[i].l > left.top()) right.push(a[i].l);
		else left.push(a[i].l);
		if (a[i].r <=  left.top()) left.push(a[i].r);
		else right.push(a[i].r);
		int szL = sz(left), szR = sz(right);
		while (left.size() > right.size()) {
			right.push(left.top());
			left.pop();
		}
		while (left.size() < right.size()) {
			left.push(right.top());
			right.pop();
		}
		int newmedian = left.top();
		 
		if (newmedian > median) {
			score[i] += szL * (newmedian - median);
			score[i] -= szR * (newmedian - median);
		}
		else {
			score[i] -= (szL -1) * (median - newmedian);
			score[i] += (szR + 1) * (median - newmedian);
		}
		median = newmedian;
	}
	
	if (K == 1) {
		cout << ans + score[sz(a) - 1] << '\n';
		return 0;
	}
	while (!left.empty()) left.pop();
	while(!right.empty()) right.pop();
	
	median = a[sz(a) - 1].l;
	left.push(a[sz(a) - 1].l);
	right.push(a[sz(a) - 1].r);
	score2[sz(a) - 1] = (a[sz(a) - 1].r - median);
	int best = min(score[sz(a) - 1], score[sz(a) - 2] + score2[sz(a) - 1]);
	for (int i(sz(a) - 2); i > 0; i--) {
		score2[i] = score2[i + 1] + abs(a[i].l - median) + abs(a[i].r - median);
		if (a[i].l > left.top()) right.push(a[i].l);
		else left.push(a[i].l);
		if (a[i].r <= left.top()) left.push(a[i].r);
		else right.push(a[i].r);
		int szL = sz(left), szR = sz(right);
		while (left.size() > right.size()) {
			right.push(left.top());
			left.pop();
		}
		while (left.size() < right.size()) {
			left.push(right.top());
			right.pop();
		}
		int newmedian = left.top();
		
		if (newmedian > median) {
			score2[i] += szL * (newmedian - median);
			score2[i] -= szR * (newmedian - median);
		}
		else {
			score2[i] -= (szL - 1) * (median - newmedian);
			score2[i] += (szR + 1) * (median - newmedian);
		}
		median = newmedian;
		best = min(best, score[i - 1] + score2[i]);
	}
	cout << best + ans << '\n';
	return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 14 / 14
• Subtask 3: 9 / 9
• Subtask 4: 32 / 32
• Subtask 5: 37 / 37