Submission #1123684

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123684		KhanhDang	Joker (BOI20_joker)	C++20	25 / 100	369 ms	66112 KiB

Joker

#include<bits/stdc++.h>
using namespace std;
#define        ll long long
#define       pll pair<ll, ll>
#define        fi first
#define        se second
#define    all(v) (v).begin(),(v).end()
#define Unique(v) sort(all(v)); (v).erase(unique(all(v)), (v).end());
const ll N = 1e6+5;
ll n, m, q;
ll x[N], y[N];
ll dd[N], ans[N];
vector<ll> adj[N];
vector<pll> qu[N];
bool dfs(ll u, ll p) {
    for (auto v : adj[u]) {
        if (v == p) continue;
        if (dd[v]) {
            if (dd[v] % 2 == dd[u] % 2)
                return true;
        } else {
            dd[v] = dd[u] + 1;
            if (dfs(v, u)) return true;
        }
    }
    return false;
}
bool check(ll mid, ll id) {
    for (int i = 1; i < id; i++) {
        adj[x[i]].push_back(y[i]);
        adj[y[i]].push_back(x[i]);
    }
    for (int i = mid+1; i <= m; i++) {
        adj[x[i]].push_back(y[i]);
        adj[y[i]].push_back(x[i]);
    }
    fill(dd+1, dd+n+1, 0);
    bool ok = false;
    for (int i = 1; i <= n; i++) {
        if (dd[i]) continue;
        dd[i] = 1;
        ok = dfs(i, i);
        if (ok) break;
    }
    for (int i = 1; i <= n; i++)
        adj[i].clear();
    return ok;
}
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    #define task "NOHOME"
    if (fopen(task".INP", "r")) {
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }
    if (fopen("task.INP", "r")) {
        freopen("task.INP", "r", stdin);
        freopen("task.OUT", "w", stdout);
    }
    cin>>n>>m>>q;
    for (int i = 1; i <= m; i++)
        cin>>x[i]>>y[i];
    for (int i = 1; i <= q; i++) {
        ll l, r; cin>>l>>r;
        qu[l].push_back({r, i});
    }
    for (int i = 1; i <= n; i++) {
        if (qu[i].empty()) continue;
        ll l = i, r = m, res = 0;
        while (l <= r) {
            ll mid = (l+r)>>1;
            if (check(mid, i)) {
                res = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
        for (auto v : qu[i]) ans[v.se] = (v.fi <= res) ;
    }
    for (int i = 1; i <= q; i++)
        cout<<(ans[i] ? "YES\n" : "NO\n");
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:55:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   55 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:58:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |         freopen("task.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:59:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         freopen("task.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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