Submission #1097160

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097160		vivkostov	Dreaming (IOI13_dreaming)	C++14	100 / 100	58 ms	22692 KiB

dreaming

#include<bits/stdc++.h>
#define endl '\n'
#include"dreaming.h"
using namespace std;
struct cell
{
    int to,cost;
};
int n,m,l,a[200005],b[200005],t[200005],used[200005],lead[200005],dp[200005],sdp[200005],mid,mind1,mind2,mind3,sma;
vector<cell>v[200005];
void read()
{
    cin>>n>>m>>l;
    for(int i=0;i<m;i++)
    {
        cin>>a[i]>>b[i]>>t[i];
    }
}
//clear
void make_dp(int beg)
{
    used[beg]=1;
    cell w;
    for(int i=0;i<v[beg].size();i++)
    {
        w=v[beg][i];
        if(!used[w.to])
        {
            make_dp(w.to);
            if(dp[beg]<dp[w.to]+w.cost)
            {
                sdp[beg]=dp[beg];
                dp[beg]=dp[w.to]+w.cost;
            }
            else sdp[beg]=max(sdp[beg],dp[w.to]+w.cost);
        }
    }
    sma=max(sma,dp[beg]+sdp[beg]);
}
void find_mid(int beg,int izm)
{
    used[beg]=1;
    cell w;
    int ma=0,sm=0,oizm=izm;
    cell ind;
    ind.cost=0;
    for(int i=0;i<v[beg].size();i++)
    {
        w=v[beg][i];
        if(!used[w.to]&&dp[w.to]>ma)
        {
            ma=dp[w.to];
            ind=w;
        }
    }
    for(int i=0;i<v[beg].size();i++)
    {
        w=v[beg][i];
        if(!used[w.to]&&w.to!=ind.to&&dp[w.to]+w.cost>sm)
        {
            sm=dp[w.to]+w.cost;
        }
    }
    izm=max(izm,sm)+ind.cost;
    if(max(ma,izm)>=max(dp[beg],oizm))
    {
        mid=beg;
    }
    else
    {
        find_mid(ind.to,izm);
    }
}
void make_lead(int beg,int le)
{
    used[beg]=2;
    lead[beg]=le;
    cell w;
    for(int i=0;i<v[beg].size();i++)
    {
        w=v[beg][i];
        if(used[w.to]<2)
        {
            make_lead(w.to,le);
        }
    }
}
void find_max_lead()
{
    int ma=-1,ind=-1;
    for(int i=0;i<n;i++)
    {
        if(ma<dp[lead[i]])
        {
            ma=dp[lead[i]];
            ind=lead[i];
        }
    }
    mind1=ind;
    ind=-1;
    ma=-1;
    for(int i=0;i<n;i++)
    {
        if(lead[i]!=mind1&&ma<dp[lead[i]])
        {
            ma=dp[lead[i]];
            ind=lead[i];
        }
    }
    mind2=ind;
    ind=-1;
    ma=-1;
    for(int i=0;i<n;i++)
    {
        if(lead[i]!=mind1&&lead[i]!=mind2&&ma<dp[lead[i]])
        {
            ma=dp[lead[i]];
            ind=lead[i];
        }
    }
    mind3=ind;
}
int travelTime(int N,int M,int L,int A[],int B[],int T[])
{
    n=N;
    m=M;
    l=L;
    for(int i=0;i<m;i++)
    {
        a[i]=A[i];
        b[i]=B[i];
        t[i]=T[i];
        cell g;
        g.to=b[i];
        g.cost=t[i];
        v[a[i]].push_back(g);
        g.to=a[i];
        v[b[i]].push_back(g);
    }
    for(int i=0;i<n;i++)
    {
        if(!used[i])make_dp(i);
    }
    memset(used,0,sizeof(used));
    for(int i=0;i<n;i++)
    {
        if(!used[i])
        {
            find_mid(i,0);
            make_lead(i,mid);
            mid=0;
        }
    }
    memset(used,0,sizeof(used));
    memset(dp,0,sizeof(dp));
    memset(sdp,0,sizeof(sdp));
    for(int i=0;i<n;i++)
    {
        if(!used[lead[i]])make_dp(lead[i]);
    }
    find_max_lead();
    if(mind2==-1)return sma;
    if(mind3==-1)return max(sma,dp[mind1]+dp[mind2]+l);
    return max(max(sma,dp[mind1]+dp[mind2]+l),dp[mind2]+dp[mind3]+2*l);
}
/*int main()
{
    read();
    cout<<travelTime(n,m,l,a,b,t)<<endl;
    return 0;
}
*/

Compilation message (stderr)

dreaming.cpp: In function 'void make_dp(int)':
dreaming.cpp:24:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<cell>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     for(int i=0;i<v[beg].size();i++)
      |                 ~^~~~~~~~~~~~~~
dreaming.cpp: In function 'void find_mid(int, int)':
dreaming.cpp:47:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<cell>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |     for(int i=0;i<v[beg].size();i++)
      |                 ~^~~~~~~~~~~~~~
dreaming.cpp:56:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<cell>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |     for(int i=0;i<v[beg].size();i++)
      |                 ~^~~~~~~~~~~~~~
dreaming.cpp: In function 'void make_lead(int, int)':
dreaming.cpp:79:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<cell>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |     for(int i=0;i<v[beg].size();i++)
      |                 ~^~~~~~~~~~~~~~
dreaming.cpp: In function 'void find_mid(int, int)':
dreaming.cpp:59:23: warning: 'ind.cell::to' may be used uninitialized in this function [-Wmaybe-uninitialized]
   59 |         if(!used[w.to]&&w.to!=ind.to&&dp[w.to]+w.cost>sm)
      |            ~~~~~~~~~~~^~~~~~~~~~~~~~

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