Submission #55013

#	Time	Username	Problem	Language	Result	Execution time	Memory
55013		ksun48	Arranging Tickets (JOI17_arranging_tickets)	C++14	10 / 100	6020 ms	764 KiB

arranging_tickets

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;

LL brute(vector<vector<LL> > z, LL n){
	LL best = z.size();
	for(LL r = 0; r < (1 << z.size()); r++){
		vector<LL> freq(n,0);
		for(int j = 0; j < z.size(); j++){
			LL c = z[j][0];
			LL d = z[j][1];
			if(r & (1 << j)){
				swap(c,d);
			}
			while(c != d){
				freq[c]++;
				c++;
				c %= n;
			}
		}
		LL maxused = 0;
		for(int j = 0; j < n; j++){
			maxused = max(maxused, freq[j]);
		}
		best = min(best, maxused);
	}
	return best;	
}

LL two(vector<vector<LL> > z, LL n){
	LL bound = 0;
	vector<int> a(2);
	for(a[0] = 0; a[0] < n; a[0]++){
		for(a[1] = 0; a[1] < n; a[1]++){
			if(a[0] == a[1]) continue;
			LL cross = 0;
			for(int j = 0; j < z.size(); j++){
				int parity = 0;
				LL c = z[j][0];
				LL d = z[j][1];
				while(c != d){
					if(c == a[0] || c == a[1]) parity ^= 1;
					c++;
					c %= n;
				}
				cross += parity;
			}
			bound = max(bound, (cross+1)/2);
		}
	}
	return bound;	
}

int main(){
	cin.sync_with_stdio(0); cin.tie(0);
	LL n, m;
	cin >> n >> m;
	// stations 1 to n
	vector<vector<LL> > z;
	for(int i = 0; i < m; i++){
		LL a, b, c;
		cin >> a >> b >> c;
		a--; b--;
		for(int j = 0; j < c; j++){
			z.push_back(vector<LL>({a,b}));
		}
	}
	LL bound = two(z, n);
	LL ans = brute(z, n);
	assert(bound <= ans);
	assert(ans <= bound + 1);
	cout << ans << '\n';
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 35
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 15