Submission #110469

#	Time	Username	Problem	Language	Result	Execution time	Memory
110469		ioilolcom	Dreaming (IOI13_dreaming)	C++14	42 / 100	354 ms	27380 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;
	for(int i=0; i<n; i++) {
		if(vis[i]) continue;
		pii s={-1,-1};
		dfs(i,-1,0,s);
		pii e={-1,-1};
		dfs(s.first,-1,0,e);
		int diameter=e.y;
		vector<int> path;
		fn(s.x,e.x,0,path);
		int sz=(int)path.size();
		int rad=diameter;
		int cur=diameter;
		ans=max(ans,cur);
		for(int j=1; j<sz; j++) {
			cur-=cost[{path[j],path[j-1]}];
			rad=min(rad,max(diameter-cur,cur));
		}
		radius.push_back(rad);
	}
	int szz=(int)radius.size();
	sort(radius.rbegin(),radius.rend());
	if(szz>1) {
		ans=max(ans,radius[0]+radius[1]+l);
	}
	if(szz>2) ans=max(ans,radius[1]+radius[2]+2*l);
	return ans;

}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:40:6: warning: unused variable 'm' [-Wunused-variable]
  int m=M;
      ^

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