Submission #728457

#	Time	Username	Problem	Language	Result	Execution time	Memory
728457		Rasoul006	Dreaming (IOI13_dreaming)	C++17	14 / 100	76 ms	47948 KiB

dreaming

#include "dreaming.h"

#include <bits/stdc++.h>

#define endl "\n"

#define F first

#define S second

#define pb push_back

typedef long long ll;

using namespace std;

const int N = 1e6+5;

const long long oo = 1e18 ;

vector <pair <ll,ll>> v[N] ;

ll n , m , ans , best , mx , dis[N] , len ;

bool vis[N] ;

void dfs (ll u , ll p , ll cost)
{
    dis[u] = cost ;
    vis[u] = true ;
    for (auto it : v[u])
    {
        if (it.F != p)
            dfs(it.F , u , cost + it.S);
    }
}

bool dfs2 (ll u , ll p , ll cost , ll gol)
{
    bool is = false ;

    for (auto it : v[u])
    {
        if (it.F != p)
            is |= dfs2(it.F , u , cost + it.S , gol) ;
    }

    is |= (u == gol);

    if (is)
        best = min (best , max(cost , len-cost));

    return is ;
}

ll p1 , p2 ;

ll far (ll p)
{
    mx = 0 ; ll ret ;

    for (int i = 1 ; i<=n ; i++)
        dis[i] = 0 ;

    dfs(p , p , 0) ;

    for (int i = 1 ; i<=n ; i++)
    {
        if (dis[i] > mx)
            ret = i , mx = dis[i] ;
        dis[i] = 0 ;
    }

    return ret ;
}

ll get (ll p)
{
    p1 = far(p);
    p2 = far(p1);
    len = mx ;

    best = oo ;
    dfs2(p1 , p1 , 0 , p2) ;
    return best ;
}


int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
    n = N ; m = M ;

    for (int i = 0 ; i<m ; i++)
    {
        v[B[i]].pb({A[i] , T[i]});
        v[A[i]].pb({B[i] , T[i]});
    }

    ans += get(1) ;

    ll bans = len ;

    for (int i = 1 ; i<=n ; i++)
    {
        if (!vis[i])
        {
            ans += get(i) ;
            break ;
        }
    }

    bans = max(bans , len) ;

    return max(bans , ans + L) ;
}

Compilation message (stderr)

dreaming.cpp: In function 'll far(ll)':
dreaming.cpp:75:12: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
   75 |     return ret ;
      |            ^~~

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