Submission #292798

#	Time	Username	Problem	Language	Result	Execution time	Memory
292798		BThero	Port Facility (JOI17_port_facility)	C++17	10 / 100	794 ms	8696 KiB

port_facility

// chrono::system_clock::now().time_since_epoch().count()
#include<bits/stdc++.h>

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << " = " << x << endl;

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int MAXN = (int)2e3 + 5;
const int MOD = (int)1e9 + 7;

int addMod(int a, int b, int m = MOD) {
  a += b;
  
  if (m <= a) {
    a -= m;
  }
  
  return a;
}

int mulMod(int a, int b, int m = MOD) {
  return a * 1ll * b % m;
}

vector<int> adj[MAXN];
int col[MAXN];
pii arr[MAXN];
int n;

bool bit(int x, int p) {
  return x & (1 << p);
}

bool cmp(pii a, pii b) {
  return a.se < b.se;
}

bool dfs(int v) {
  for (int to : adj[v]) {
    if (col[to] == -1) {
      col[to] = 1 - col[v];
      
      if (dfs(to)) {
        return 1;
      }
    }
    else if (col[to] == col[v]) {
      return 1;
    }
  }
  
  return 0;
}

void solve() {
  scanf("%d", &n);
  
  for (int i = 1; i <= n; ++i) {
    scanf("%d %d", &arr[i].fi, &arr[i].se);
  }
  
  sort(arr + 1, arr + n + 1, cmp);
  
  for (int i = 1; i <= n; ++i) {
    for (int j = i + 1; j <= n; ++j) {
      if (arr[i].fi < arr[j].fi && arr[i].se > arr[j].fi) {
        for (int k = j + 1; k <= n; ++k) {
          if (arr[j].fi < arr[k].fi && arr[j].se > arr[k].fi) {
            if (arr[i].fi < arr[k].fi && arr[i].se > arr[k].fi) {
              printf("0\n");
              return;
            }
          }
        }
      
        adj[i].pb(j);
        adj[j].pb(i);
      }
    }
  }
  
  fill(col + 1, col + n + 1, -1);
  int ans = 1;
  
  for (int i = 1; i <= n; ++i) {
    if (col[i] == -1) {
      col[i] = 0;
      assert(!dfs(i));
      ans = addMod(ans, ans);
    }
  }
  
  printf("%d\n", ans);
}

int main() {
  int tt = 1;
  
  while (tt--) {
    solve();
  }

  return 0;
}

Compilation message (stderr)

port_facility.cpp: In function 'void solve()':
port_facility.cpp:65:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   65 |   scanf("%d", &n);
      |   ~~~~~^~~~~~~~~~
port_facility.cpp:68:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |     scanf("%d %d", &arr[i].fi, &arr[i].se);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22