Submission #618853

#	Time	Username	Problem	Language	Result	Execution time	Memory
618853		Zanite	Dynamic Diameter (CEOI19_diameter)	C++17	24 / 100	5075 ms	20764 KiB

diameter

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

using ll	= long long;
using pll	= pair<ll, ll>;
using Edge	= pair<ll, pll>;

#define fi	first
#define se	second

const int maxN	= 1e5 + 5;

ll n, q, w;
set<pll> adj[maxN];
vector<Edge> edges;

vector<ll> dist;

void dfs(ll cur, ll par, ll cdist) {
	dist[cur] = cdist;
	for (auto &[nxt, w] : adj[cur]) {
		if (nxt == par) continue;
		dfs(nxt, cur, cdist+w);
	}
}

ll solve() {
	dist.assign(n+1, 0);
	dfs(1, 0, 0);

	ll e1 = -1, mx = -1;
	for (ll i = 1; i <= n; i++) {
		if (dist[i] > mx) {
			mx = dist[i];
			e1 = i;
		}
	}

	dist.assign(n+1, 0);
	dfs(e1, 0, 0);

	ll ret = 0;
	for (ll i = 1; i <= n; i++) {
		ret = max(ret, dist[i]);
	}
	return ret;
}

int main() {
	scanf("%lld %lld %lld", &n, &q, &w);
	for (ll a, b, c, i = 1; i < n; i++) {
		scanf("%lld %lld %lld", &a, &b, &c);
		adj[a].insert({b, c});
		adj[b].insert({a, c});
		edges.push_back({c, {a, b}});
	}
	ll last = 0;
	for (ll d, e, i = 1; i <= q; i++) {
		scanf("%lld %lld", &d, &e);
		d = (d + last) % (n - 1);
		e = (e + last) % w;

		auto &[w, p] = edges[d];

		adj[p.fi].erase({p.se, w});
		adj[p.se].erase({p.fi, w});

		edges[d].fi = e;
		adj[p.fi].insert({p.se, e});
		adj[p.se].insert({p.fi, e});

		/*
		for (ll i = 1; i <= n; i++) {
			cout << i << ": ";
			for (auto &[j, k] : adj[i]) {
				cout << "{" << j << ", " << k << "} ";
			}
			cout << '\n';
		}
		*/

		last = solve();
		printf("%lld\n", last);
	}
}

Compilation message (stderr)

diameter.cpp: In function 'int main()':
diameter.cpp:50:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |  scanf("%lld %lld %lld", &n, &q, &w);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:52:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |   scanf("%lld %lld %lld", &a, &b, &c);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:59:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |   scanf("%lld %lld", &d, &e);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27