Submission #561465

#	Time	Username	Problem	Language	Result	Execution time	Memory
561465		Iwanttobreakfree	Dreaming (IOI13_dreaming)	C++98	18 / 100	46 ms	16316 KiB

dreaming

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include "dreaming.h"
using namespace std;
typedef long long ll;
int last_node,max_dist;
void dfs(int a,int par,vector<vector<pair<int,int>>>& g,int& d,vector<bool>& seen,vector<pair<int,int>>& p){
    seen[a]=true;
    for(auto x:g[a]){
        if(x.first==par)continue;
        d+=x.second;
        p[x.first]={a,x.second};
        dfs(x.first,a,g,d,seen,p);
        d-=x.second;
    }
    if(d>max_dist){
        max_dist=d;
        last_node=a;
    }
}
int mid(int a,vector<pair<int,int>>& p){
    vector<int> path;
    int ans=1e9,cnt=0;
    while(a!=-1){
        path.push_back(p[a].second);
        a=p[a].first;
    }
    for(int i=0;i<path.size();i++){
        cnt+=path[i];
        ans=min(ans,max(cnt,max_dist-cnt));
    }
    return ans;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    vector<vector<pair<int,int>>> g(N,vector<pair<int,int>>());
    vector<bool> seen(N,false);
    for(int i=0;i<M;i++){
        g[A[i]].push_back({B[i],T[i]});
        g[B[i]].push_back({A[i],T[i]});
    }
    vector<int> best;
    vector<pair<int,int>>p(N);
    int ans=0;
    for(int i=0;i<N;i++){
        if(!seen[i]){
            max_dist=-1;
            int di=0;
            dfs(i,i,g,di,seen,p);
            p[last_node].first=-1;
            max_dist=-1;
            dfs(last_node,last_node,g,di,seen,p);
            ans=max(ans,max_dist);
            best.push_back(mid(last_node,p));
        }
    }
    sort(best.rbegin(),best.rend());
    if(best.size()>1)ans=ans+L+best[1];
    for(int i=2;i<best.size();i++){
        ans=max(ans,2*L+best[1]+best[i]);
    }
    //for(int x:best)cout<<x<<' ';
    return ans;
}
/*int main(){
    int n,m,l;
    cin>>n>>m>>l;
    int a[m],b[m],t[m];
    for(int i=0;i<m;i++)cin>>a[i]>>b[i]>>t[i];
    cout<<travelTime(n,m,l,a,b,t);
}*/

Compilation message (stderr)

dreaming.cpp: In function 'int mid(int, std::vector<std::pair<int, int> >&)':
dreaming.cpp:30:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |     for(int i=0;i<path.size();i++){
      |                 ~^~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:60:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     for(int i=2;i<best.size();i++){
      |                 ~^~~~~~~~~~~~

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