Submission #296601

#	Time	Username	Problem	Language	Result	Execution time	Memory
296601		williamMBDK	Dreaming (IOI13_dreaming)	C++14	18 / 100	151 ms	21996 KiB

dreaming

#include<bits/stdc++.h>
#include "dreaming.h"
#define int long long
using namespace std;
int N, M;
vector<vector<pair<int,int>>> adj (1e5), distances (1e5);
vector<int> mxdist (1e5), mxinnerdist(1e5);
vector<vector<int>> getcomps(){
	vector<bool> v (N);
	vector<vector<int>> res;
	for(int i = 0; i < N; i++){
		if(!v[i]){
			queue<int> q;
			q.push(i);
			res.push_back({});
			while(!q.empty()){
				int curr = q.front(); q.pop();
				if(v[curr]) continue;
				v[curr] = 1;
				res[res.size() - 1].push_back(curr);
				for(auto e : adj[curr]) q.push(e.first);
			}
		}
	}
	return res;
}
int dfs1(int node, int p){
	for(int i = 0; i < adj[node].size(); i++){
		if(adj[node][i].first == p) continue;
		distances[node][i].first = dfs1(adj[node][i].first, node) + adj[node][i].second;
		distances[node][i].second = i;
	}
	sort(distances[node].rbegin(), distances[node].rend());
	if(distances[node].size() < 2) return 0; // right?
	return distances[node][0].first;
}
void dfs2(int node, int p, int mxp){
	if(p == -1){
		if(adj[node].size() > 0) mxdist[node] = distances[node][0].first;
		else mxdist[node] = 0;
		if(adj[node].size() >= 2){
			mxinnerdist[node] = distances[node][0].first + distances[node][1].first;
		}else if(adj[node].size() == 1){
			mxinnerdist[node] = distances[node][0].first;
		}
	}else if(adj[node].size() == 1){
		mxdist[node] = mxp;	
		mxinnerdist[node] = mxp;
	}else{
		mxdist[node] = max(mxp, distances[node][0].first); // right?
		mxinnerdist[node] = mxp + distances[node][0].first;
		if(adj[node].size() > 2){
			mxinnerdist[node] = max(mxinnerdist[node], distances[node][0].first + distances[node][1].first);
		}
	}
	// cout << mxdist[node] << " " << node << endl;
	for(int i = 0; i < adj[node].size(); i++){
		if(adj[node][i].first == p) continue;
		int t = mxp;
		if(distances[node][0].second == i){
			if(distances[node].size() >= 3) t = max(t, distances[node][1].first);
		}else{
			t = max(t, distances[node][0].first); //right?
		}
		t += adj[node][i].second;
		dfs2(adj[node][i].first, node, t);
	}
}
signed travelTime(signed _N, signed _M, signed L, signed A[], signed B[], signed T[]) {
	N = _N;
	M = _M;
	for(int i = 0; i < M; i++){
		adj[A[i]].push_back({B[i],T[i]});
		adj[B[i]].push_back({A[i],T[i]});
		distances[A[i]].push_back({-1,-1});
		distances[B[i]].push_back({-1,-1});
	}
	vector<vector<int>> components = getcomps();
	int C = components.size();
	vector<int> compdists (C, INT_MAX);
	int res = 0;
	for(int i = 0; i < C; i++){
		// cout << "root" << components[i][0] << endl;
		dfs1(components[i][0], -1);
		dfs2(components[i][0], -1, 0);
		for(int j = 0; j < components[i].size(); j++){
			compdists[i] = min(compdists[i], mxdist[components[i][j]]);
			res = max(res, mxinnerdist[components[i][j]]);
		}
	}
	sort(compdists.rbegin(), compdists.rend());
	if(C == 1){
		return res;
	}else if(C == 2){
		return max(L + compdists[0] + compdists[1], res);
	}else{
		return max(res, max(L + compdists[0] + compdists[1], 2 * L + compdists[1] + compdists[2]));
	}
}

Compilation message (stderr)

dreaming.cpp: In function 'long long int dfs1(long long int, long long int)':
dreaming.cpp:28:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |  for(int i = 0; i < adj[node].size(); i++){
      |                 ~~^~~~~~~~~~~~~~~~~~
dreaming.cpp: In function 'void dfs2(long long int, long long int, long long int)':
dreaming.cpp:57:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |  for(int i = 0; i < adj[node].size(); i++){
      |                 ~~^~~~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:86:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   86 |   for(int j = 0; j < components[i].size(); j++){
      |                  ~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 18 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23