Submission #744545

#	Time	Username	Problem	Language	Result	Execution time	Memory
744545		RushB	Road Closures (APIO21_roads)	C++17	31 / 100	2073 ms	31644 KiB

roads

#include "roads.h"
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
long long dp[N][2];
int X, p[N];
vector<array<int, 2>> adj[N];
vector<int> rec;
set<int> S;
bitset<N> enb, mark;

void dfs(int v, int p) {
	if (enb[v]) return void(dp[v][0] = dp[v][1] = 0);

	rec.push_back(v);
	mark[v] = true;

	long long dif = 0, ans = 0, mx = 0;
	vector<long long> V;
	V.reserve(adj[v].size());

	for (auto P: adj[v]) {
		int u = P[0], w = P[1];
		if (u == p) continue;
		dfs(u, v);
		dif += dp[u][0];
		V.push_back(w + dp[u][1] - dp[u][0]);
	}
	sort(V.rbegin(), V.rend());
	for (int i = 0; i <= X && i <= V.size(); i++) {
		if (i) ans += V[i - 1];
		mx = max(mx, ans);
		if (i + 1 == X) dp[v][1] = mx + dif;
	}
	if (V.size() + 1 < X) dp[v][1] = mx + dif;
	dp[v][0] = mx + dif;
}

vector<long long> minimum_closure_costs(int n, vector<int> U, vector<int> V, vector<int> W) {
	long long all = 0;
	for (int i = 0; i < U.size(); i++) {
		adj[U[i]].push_back({V[i], W[i]});
		adj[V[i]].push_back({U[i], W[i]});
		all += W[i];
	}
	iota(p, p + n, 0), sort(p, p + n, [&](const int x, const int y) {return adj[x].size() < adj[y].size();});
	for (int i = 0; i < n; i++) S.insert(i);

	vector<long long> re(n);
	re[0] = all;
	for (int i = 1, ptr = 0; i < n; i++) {
		X = i; 
		for (;ptr < n && adj[p[ptr]].size() <= i; ptr++) {
			int v = p[ptr];
			for (auto P: adj[v]) if (enb[P[0]]) all -= P[1];
			enb[v] = true;
			S.erase(v);
		}
		long long ans = 0;
		for (auto v: S) if (!mark[v]) {
			dfs(v, v);
			ans += dp[v][0];
		}
		if (i >= 500) assert(S.size() <= 1000);

		for (auto v: rec) mark[v] = 0;
		rec.clear();

		re[i] = all - ans;
	}
	return re;
}

Compilation message (stderr)

roads.cpp: In function 'void dfs(int, int)':
roads.cpp:30:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |  for (int i = 0; i <= X && i <= V.size(); i++) {
      |                            ~~^~~~~~~~~~~
roads.cpp:35:19: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   35 |  if (V.size() + 1 < X) dp[v][1] = mx + dif;
      |      ~~~~~~~~~~~~~^~~
roads.cpp: In function 'std::vector<long long int> minimum_closure_costs(int, std::vector<int>, std::vector<int>, std::vector<int>)':
roads.cpp:41:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |  for (int i = 0; i < U.size(); i++) {
      |                  ~~^~~~~~~~~~
roads.cpp:53:39: warning: comparison of integer expressions of different signedness: 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   53 |   for (;ptr < n && adj[p[ptr]].size() <= i; ptr++) {
      |                    ~~~~~~~~~~~~~~~~~~~^~~~

• Subtask 1: 0 / 5
• Subtask 2: 7 / 7
• Subtask 3: 14 / 14
• Subtask 4: 10 / 10
• Subtask 5: 0 / 17
• Subtask 6: 0 / 25
• Subtask 7: 0 / 22