Submission #1298969

#	Time	Username	Problem	Language	Result	Execution time	Memory
1298969		hoa208	Aesthetic (NOI20_aesthetic)	C++20	20 / 100	230 ms	38424 KiB

Aesthetic

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; i++)
#define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; i--)
#define pa pair<ll, ll>
#define fi first
#define se second
#define bit(mask, j) ((mask >> j) & 1)
const   ll mod = 1e9 + 7;
const   ll INF = 1e18;
//--------------------------------------------------------------------
const ll N = 3e5 + 10;
struct ED {
	ll u, v, w;
} ed[N];
vector<pa> g[N];
ll n, m;
namespace sub3 {
	bool check() {
		return m == n - 1;
	}
	ll f[N];
	bool dx[N];
	pa par[N];
	void dfs(ll u, ll p) {
		for(auto e : g[u]) {
			ll v = e.fi, id = e.se;
			if(v == p) continue;
			par[v] = {u, id};
			f[v] = f[u] + ed[id].w;
			dfs(v, u);
		}
	}
	void slove() {
		FOR(i, 1, m) {
			ll u = ed[i].u, v = ed[i].v, w = ed[i].w;
			g[u].push_back({v, i});
			g[v].push_back({u, i});
		}
		dfs(1, 0);
		vector<ll> vt;
		ll u = n;
		while(u != 1) {
			ll v = par[u].fi, id = par[u].se;
			dx[id] = 1;
			u = v;
		}
		ll ans = f[n];
		ll mx = -INF;
		FORD(i, m, 1) {
			if(dx[i]) {
				ans = max(ans, f[n] + mx);
			}
			mx = max(ed[i].w, mx);
		}
		cout << ans;
	}
}
namespace sub1 {
	bool check() {
		return n <= 2000 && m <= 2000;
	}
	const ll N = 2003;
	ll d[N];
	void DJK() {
		priority_queue<pa, vector<pa>, greater<pa>> q;
		q.push({0, 1});
		fill(d + 1, d + n + 1, INF);
		d[1] = 0;
		while(!q.empty()) {
			ll u = q.top().se, du = q.top().fi;
			q.pop();
			if(du != d[u]) continue;
			for(auto e : g[u]) {
				ll v = e.fi, w = ed[e.se].w;
				if(d[v] > d[u] + w) {
					d[v] = d[u] + w;
					q.push({d[v], v});
				}
			}
		}
	}
	void slove() {
        FOR(i, 1, m) {
			ll u = ed[i].u, v = ed[i].v, w = ed[i].w;
			g[u].push_back({v, i});
			g[v].push_back({u, i});
		}
		DJK();
		ll ans = d[n];
		ll mx = ed[m].w;
		FORD(i, m - 1, 1) {
			ed[i].w = ed[i].w + mx;
			DJK();
			ans = max(ans, d[n]);
			ed[i].w = ed[i].w - mx;
			mx = max(ed[i].w, mx);
		}
		cout << ans;
	}
}
void hbmt() {
	cin >> n >> m;
	FOR(i, 1, m) {
		ll u, v, w;
		cin >> u >> v >> w;
		ed[i] = {u, v, w};
	}
	if(sub1::check()) return sub1::slove();
	if(sub3::check()) return sub3::slove();

}

int main() {
	
	ios_base::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);

	#define NAME "hbmt"
	if(fopen(NAME".inp", "r")) {
		freopen(NAME".inp", "r", stdin);
		freopen(NAME".out", "w", stdout);
	}
	
	//int t;cin>>t;while(t--)
	hbmt();
	return 0;
}

Compilation message (stderr)

Aesthetic.cpp: In function 'int main()':
Aesthetic.cpp:122:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  122 |                 freopen(NAME".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Aesthetic.cpp:123:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  123 |                 freopen(NAME".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 7 / 7
• Subtask 4: 0 / 15
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22
• Subtask 7: 0 / 27