Submission #1093509

#	Time	Username	Problem	Language	Result	Execution time	Memory
1093509		duyhoanho	Joker (BOI20_joker)	C++17	0 / 100	1 ms	860 KiB

Joker

#include<bits/stdc++.h>
#define int long long
#define forinc(i,a,b) for(int i=a;i<=b;i++)
#define fi first
#define se second
#define pii pair<int,int>
#define pb push_back
using namespace std;
const int N = 2e3+10;
int n,m,q,fre[N];
bool ok;
pii a[N];
vector<int> ad[N];
void bfs(int x)
{
    queue<int> q;
    fre[x] = 0;
    q.push(x);
    while(q.size())
    {
        int u = q.front();q.pop();
        for(int v : ad[u])
        {
            if(fre[v] == fre[u])
            {
                ok = 1;
                return;
            }
            if(fre[v] != -1) continue;
            fre[v] = 1 - fre[u];
            q.push(v);
        }
    }
}
bool qu(int l,int r)
{
    ok = 0;
    forinc(i,1,m)
    {
        if(l<=i && i<=r) continue;
        int x,y;
        tie(x,y) = a[i];
        ad[x].pb(y);
        ad[y].pb(x);
    }

    for(int i=1;i<=n;i++) fre[i] = -1;
    for(int i=1;i<=n;i++)
    {
        if(fre[i] == -1)
        {
            bfs(i);
            if(ok == 1) return true;
        }
    }
    return false;
}
int32_t main()
{
    if(fopen("task.inp","r"))
    {
        freopen("task.inp","r",stdin);
        freopen("task.out","w",stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m>>q;
    forinc(i,1,m)
    {
        int x,y;
        cin>>x>>y;
        a[i] = {x,y};
    }
    while(q--)
    {
        int l,r;
        cin>>l>>r;
        cout<< (qu(l,r) ? "YES\n" : "NO\n");
    }


}

Compilation message (stderr)

Joker.cpp: In function 'int32_t main()':
Joker.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         freopen("task.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen("task.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29