Submission #1172739

#	Time	Username	Problem	Language	Result	Execution time	Memory
1172739		Tsagana	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	198 ms	24904 KiB

Main

#include<bits/stdc++.h>

#define IOS ios_base::sync_with_stdio(false);cin.tie();cout.tie();
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define pq priority_queue
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define pp pop_back
#define F first
#define S second

using namespace std;

vector<pair<int, int>> adj[200010];
vector<int> vis[2];
void bfs(int s, int t) {
	vis[t][s]=0;
	pq<pair<int, int>> q;
	q.push({0, s});
	while (!q.empty()) {
		int w = -q.top().F;
		s = q.top().S;
		q.pop();
		if (vis[t][s] < w) continue ;
		for (auto i: adj[s]) {
			if (w + i.S < vis[t][i.F]) {
				vis[t][i.F] = w + i.S;
				q.push({-vis[t][i.F], i.F});
			}
		}
	}
}

void solve () {
	int n, m, s, t, l, k;
	cin >> n >> m >> s >> t >> l >> k;
	for (int i = 0; i < m; i++) {
		int a, b, c;
		cin >> a >> b >> c;
		adj[a].pb({b, c});
		adj[b].pb({a, c});
	}
	vis[0] = vis[1] = vector<int>(n+1, 2e18);
	bfs(s, 0);
	bfs(t, 1);
	if (vis[0][t] <= k) {
		cout << (n * (n - 1)) / 2 << '\n';
		return ;
	}
	int ans = 0;
	sort(all(vis[0]));
	sort(rall(vis[1]));
	for (int i = 0, r = 1; i < n; i++) {
		while (r <= n && vis[0][i] + vis[1][r] + l > k) r++;
		ans += n - r + 1;
	}
	cout << ans << '\n';
}
signed main() {IOS solve(); return 0;}

• Subtask 1: 8 / 8
• Subtask 2: 16 / 16
• Subtask 3: 29 / 29
• Subtask 4: 47 / 47