Submission #1111228

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111228		nikolashami	Dreaming (IOI13_dreaming)	C++17	18 / 100	65 ms	15816 KiB

dreaming

#include <bits/stdc++.h>
using namespace std;
 
#include "dreaming.h"
 
const int N=1e5+4;
vector<array<int,2>>adj[N];
int d[N][2],vis[N];
 
vector<int>passed,path;
 
void dfs(int u,bool x){
    passed.push_back(u);
    vis[u]=1;
    for(auto&[v,w]:adj[u]){
        if(vis[v])
            continue;
        d[v][x]=d[u][x]+w;
        dfs(v,x);
    }
}
 
bool findpath(int u,int p,int s,int e){
    if(u==e){
    	path.push_back(e);
    	return 1;
    }
    for(auto&[v,w]:adj[u]){
    	if(v==p)
    		continue;
    	if(findpath(v,u,s,e)){
    		path.push_back(v);
    		return 1;
    	}
    }
    return 0;
}
 
void unq(vector<int>&v){
    sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
}
 
int findmxlen(int node){
    d[node][0]=0;
    dfs(node,0);
    unq(passed);
    int mx=-1,kraj1,kraj2;
    for(int u:passed){
        if(d[u][0]>mx){
            mx=d[u][0];
            kraj1=u;
        }
        vis[u]=0;
    }
    passed.clear();
    d[kraj1][0]=0;
    dfs(kraj1,0);
    unq(passed);
    mx=-1;
    for(int u:passed){
        if(d[u][0]>mx){
            mx=d[u][0];
            kraj2=u;
        }
        vis[u]=0;
    }
    passed.clear();
    d[kraj2][1]=0;
    dfs(kraj2,1);
    unq(passed);
    for(int u:passed)
        vis[u]=0;
    path.clear();
    findpath(kraj1,-1,kraj1,kraj2);
    unq(passed);
    for(int u:passed)
        vis[u]=1;
    int mnmxlen=2e9;
    for(int v:path)
        mnmxlen=min(mnmxlen,max(d[v][0],d[v][1]));
    passed.clear();
    return mnmxlen;
}
 
int jednostablo(int node=1){
    d[node][0]=0;
    dfs(node,0);
    int mx=-1,kraj1,kraj2;
    for(auto&u:passed){
        if(d[u][0]>mx){
            mx=d[u][0];
            kraj1=u;
        }
        vis[u]=0;
    }
    passed.clear();
    d[kraj1][0]=0;
    dfs(kraj1,0);
    mx=-1;
    for(auto&u:passed)
        if(d[u][0]>mx)
            mx=d[u][0];
    return mx;
}
 
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    int n=N,m=M,l=L;
 
    for(int i=0,u,v,w;i<m;++i){
        u=A[i];
        v=B[i];
        w=T[i];
        ++u,++v;
        adj[u].push_back({v,w});
        adj[v].push_back({u,w});
    }
 
    if(m==n-1)
        return jednostablo();
 
    vector<int>poludijametri;
 
    for(int i=1;i<=n;++i){
        if(vis[i])
            continue;
        poludijametri.push_back(findmxlen(i));
    }
 
    sort(poludijametri.rbegin(),poludijametri.rend());
  
    int ans=poludijametri[0]+poludijametri[1]+l;
    if(poludijametri.size()>2)
        ans=max(ans,poludijametri[1]+poludijametri[2]+2*l);
 
    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'int jednostablo(int)':
dreaming.cpp:89:21: warning: unused variable 'kraj2' [-Wunused-variable]
   89 |     int mx=-1,kraj1,kraj2;
      |                     ^~~~~
dreaming.cpp:99:8: warning: 'kraj1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   99 |     dfs(kraj1,0);
      |     ~~~^~~~~~~~~
dreaming.cpp: In function 'int findmxlen(int)':
dreaming.cpp:75:13: warning: 'kraj2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   75 |     findpath(kraj1,-1,kraj1,kraj2);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
dreaming.cpp:75:13: warning: 'kraj1' may be used uninitialized in this function [-Wmaybe-uninitialized]

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