Submission #1072229

#	Time	Username	Problem	Language	Result	Execution time	Memory
1072229		7again	Mecho (IOI09_mecho)	C++14	0 / 100	14 ms	15716 KiB

mecho

#include <bits/stdc++.h>
#define int long long
#define endl "\n"
#define f first
#define s second
#define pb push_back
#define in insert
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define yes cout<<"Yes\n"
#define no cout<<"No\n"
#define FAST ios::sync_with_stdio(0);cout.tie(0);cin.tie(0)

using namespace std ;

void setIO(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}

const int N = 300000 , MOD = 1e9+7 ;

//bool inside(int x,int y){return(x<n&&y<m&&x>-1&&y>-1&&a[x][y]!='#');}

//int dx[4]{1 , -1 , 0 , 0} , dy[4]{0 , 0 , 1 , -1} ;

vector <pair <int , int>> v[N] ;
int n , k , m ;
bool ok ;
int c[N] , vis[N] ;

void dfs(int x)
{
    if(vis[x])
        return ;

    vis[x] = 1 ;
    for(auto t : v[x])
    {
        if(t.s > m)
            continue ;

        if(c[t.f] == c[x])
        {
            ok = 0 ;
            return ;
        }

        c[t.f] = 1 - c[x] ;
        dfs(t.f) ;
    }
}
void slv()
{
    cin >> n >> k ;

    for(int i = 0 ; i < k ; i++)
    {
        int x , y ;
        cin >> x >> y ;
        x-- ;
        y-- ;

        v[x].pb({y , i}) ;
        v[y].pb({x , i}) ;
    }

    int l = 0 , r = k ;
    while(l + 1 < r)
    {
        m = l + (r - l) / 2 ;
        ok = 1 ;
        fill(c , c + n , -1) ;
        fill(vis , vis + n , 0) ;
        c[0] = 0 ;
        dfs(0) ;

        if(ok)
            l = m ;
        else
            r = m ;
    }

    cout << l + 2 ;
}
main()
{
    //setIO("lasers") ;

    FAST ;

    int t = 1 ;
    //cin >> t ;

    while(t--)
        slv() ;
}

Compilation message (stderr)

mecho.cpp:83:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   83 | main()
      | ^~~~
mecho.cpp: In function 'void setIO(std::string)':
mecho.cpp:16:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 | void setIO(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:16:66: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 | void setIO(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 100