Submission #110470

#	Time	Username	Problem	Language	Result	Execution time	Memory
110470		ioilolcom	Dreaming (IOI13_dreaming)	C++14	100 / 100	564 ms	29656 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
#define y second
#define x  first
#define ll long long int
#define pb push_back
#define pii pair<int,int>
using namespace std;
const int N=1e5+7;
vector<pair<int,int> > adj[N];
bool vis[N];
void dfs(int node,int p,int length,pii &ans){
	vis[node]=1;
	for(auto vertice:adj[node]) {
		if(vertice.x==p) {
			continue;
		}
		dfs(vertice.x,node,length+vertice.y,ans);
	}
	if(length>ans.y) {
		ans.x=node;
		ans.y=length;
	}
}
bool fn(int s,int e,int p,vector<int> &path){
	if(s==e) {
		return true;
	}
	for(auto v:adj[s]) {
		if(v.x==p) continue;
		if(fn(v.x,e,s,path)) {
			path.push_back(v.x);
			return true;
		}
	}
	return false;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
	int n=N;
	int m=M;
	int l=L;
	vector<int> radius;
	map<pair<int,int>,int> cost;
	for(int i=0; i<M; i++) {
		int u=A[i];
		int v=B[i];
		int w=T[i];
		adj[u].pb({v,w});
		adj[v].pb({u,w});
		cost[{u,v}]=cost[{v,u}]=w;
	}
	int ans = 0;
	vector <int> a;
	for(int i = 0; i < N; i++) {
		if(vis[i]) continue;
		pair <int, int> f = make_pair(-1, -1);
		dfs(i, -1, 0, f);
		pair <int, int> s = make_pair(-1, -1);
		dfs(f.first, -1, 0, s);
		ans = max(ans, s.second);
		//path.clear();
		vector<int> path;
		fn(f.first,  s.first,-1,path);
		path.push_back(f.first);
		int c = s.second;
		int cur = s.second;
		for(int j = 1; j < path.size(); j++) {
			cur -= cost[make_pair(path[j], path[j - 1])];
			c = min(c, max(cur, s.second - cur));
		}
		a.push_back(c);
	}
	sort(a.rbegin(), a.rend());
	if(a.size() > 1)
		ans = max(ans, a[0] + a[1] + L);
	if(a.size() > 2)
		ans = max(ans, a[1] + a[2] + 2 * L);
	return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:67:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j = 1; j < path.size(); j++) {
                  ~~^~~~~~~~~~~~~
dreaming.cpp:39:6: warning: unused variable 'n' [-Wunused-variable]
  int n=N;
      ^
dreaming.cpp:40:6: warning: unused variable 'm' [-Wunused-variable]
  int m=M;
      ^
dreaming.cpp:41:6: warning: unused variable 'l' [-Wunused-variable]
  int l=L;
      ^

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