Submission #916779

#	Time	Username	Problem	Language	Result	Execution time	Memory
916779		Ninedesu	Dreaming (IOI13_dreaming)	C++14	100 / 100	120 ms	20048 KiB

dreaming

#include "dreaming.h"
#include<bits/stdc++.h>
#define ll long long
#define pii pair<ll,int>
using namespace std;

const int N=1e5+1;
ll a,adis,b,bdis,c,cdis;
ll dis[N],rdis[N];
bool chk;
bitset<N>vis;
vector<pii>adj[N];
vector<int>center;

bool comp(int a,int b){
    return rdis[a]>rdis[b];
}

void dfs1(int u,int p,bool boo){
    vis[u]=true;
    if(!boo&&dis[u]>adis){
        a=u;
        adis=dis[u];
    }
    else if(boo&&dis[u]>bdis){
        b=u;
        bdis=dis[u];
    }
    //if(boo)cout << u << ',' << dis[u] << ' ';
    for(pii wv:adj[u]){
        ll w=wv.first;
        int v=wv.second;
        if(v==p)continue;
        dis[v]=dis[u]+w;
        dfs1(v,u,boo);
    }
}

void dfs2(int u,int p){
    if(u==a){
        chk=true;
        c=u;
        cdis=bdis;
        //cout << u << ',' << bdis << ' ';
        return ;
    }
    for(pii wv:adj[u]){
        int v=wv.second;
        if(v==p)continue;
        dfs2(v,u);
        if(chk){
            //cout << u << ',' << bdis-dis[u] << ' ';
            if(max(dis[u],bdis-dis[u])<cdis){
                c=u;
                cdis=max(dis[u],bdis-dis[u]);
            }
            return ;
        }
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for(int i=0; i<M; i++){
        adj[A[i]].push_back({T[i],B[i]});
        adj[B[i]].push_back({T[i],A[i]});
    }
    ll mx=0,smx=0,tmx=0,mxb=0;
    for(int i=0; i<N; i++){
        if(vis[i])continue;
        a=i;
        adis=0,bdis=0;
        chk=false;
        dis[i]=0;
        dfs1(i,-1,0);
        dis[a]=0;
        b=a,c=a;
        dfs1(a,-1,1);
        //cout << bdis << '\n';
        dfs2(b,-1);
        center.push_back(c);
        rdis[c]=cdis;
    }
    sort(center.begin(),center.end(),comp);
    for(int i=1; i<center.size(); i++){
        adj[center[i]].push_back({L,center[0]});
        adj[center[0]].push_back({L,center[i]});
    }
    dis[0]=0;
    adis=0,bdis=0,a=0;
    dfs1(0,-1,0);
    b=a;
    dis[a]=0;
    dfs1(a,-1,1);
    return bdis;
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:84:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |     for(int i=1; i<center.size(); i++){
      |                  ~^~~~~~~~~~~~~~
dreaming.cpp:67:8: warning: unused variable 'mx' [-Wunused-variable]
   67 |     ll mx=0,smx=0,tmx=0,mxb=0;
      |        ^~
dreaming.cpp:67:13: warning: unused variable 'smx' [-Wunused-variable]
   67 |     ll mx=0,smx=0,tmx=0,mxb=0;
      |             ^~~
dreaming.cpp:67:19: warning: unused variable 'tmx' [-Wunused-variable]
   67 |     ll mx=0,smx=0,tmx=0,mxb=0;
      |                   ^~~
dreaming.cpp:67:25: warning: unused variable 'mxb' [-Wunused-variable]
   67 |     ll mx=0,smx=0,tmx=0,mxb=0;
      |                         ^~~

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