Submission #31102

#	Time	Username	Problem	Language	Result	Execution time	Memory
31102		RezwanArefin01	Port Facility (JOI17_port_facility)	C++14	22 / 100	6000 ms	59776 KiB

port_facility

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
 
const int maxn = 1e6 + 10;
vector<int> adj[maxn]; 
int col[maxn], n; 
 
struct range{
    int l, r; 
    bool operator < (const range &p) const {
        return l == p.l ? r < p.r : l < p.l;
    }
} v[maxn];
 
bool cant(int i, int j) {
    return (v[i].l < v[j].l && v[j].l < v[i].r && v[j].r > v[i].r);
}
 
bool bfs(int r) {
    col[r] = 0; 
    queue<int> Q;
    Q.push(r); 
    while(!Q.empty()) {
        int u = Q.front(); Q.pop(); 
        for(int v : adj[u]) {
            if(col[v] == -1) {
                col[v] = col[u] ^ 1; 
                Q.push(v);
            } else if(col[v] == col[u]) return 0;
        }
    } return 1; 
}
int p[maxn * 2 + 100];
int find(int u) { return p[u] == u ? u : p[u] = find(p[u]); }
void construct() {
    sort(v, v+n);
    range q[n]; 
    for(int i = 0; i <= 2*n; i++) 
        p[i] = i;
    for(int i = 0; i < n; i++) {
        range xx = {v[i].r, 0}; 
        int x = lower_bound(v, v+n, v[i]) - v; 
        int y = upper_bound(v, v+n, xx) - v;
        for(int j = x; j <= y; j++) {
            if(cant(i, j) || cant(j, i)) {
                adj[i].push_back(j);
                adj[j].push_back(i); 
                p[find(i)] = find(j + n);
                p[find(j)] = find(i + n);


                if(find(i) == find(i + n) || find(j) == find(j + n)) 
                    { puts("0"); exit(0); }
                //cout << i << " " << v[j].r << endl;
            }
        }   
    }
}
int main(int argc, char const *argv[]) {
#ifdef LOCAL_TESTING
    freopen("in", "r", stdin);
#endif
    cin >> n; 
    for(int i = 0; i < n; i++) 
        cin >> v[i].l >> v[i].r; 
 
    construct(); 
    int comp = 0;

    memset(col, -1, sizeof col);
    for(int i = 0; i < n; i++) {
        if(col[i] == -1) {
            comp++;
            if(!bfs(i)) return cout << 0 << endl, 0; 
            //for(int j=0; j < n; j++) cout << col[i] <<" "; cout << endl;
        }
    }
    int ans = 1; 
    for(int i = 0; i < comp; i++) {
        ans = (ans * 2) % ll(1e9 + 7); 
    } cout << ans << endl;
}

Compilation message (stderr)

port_facility.cpp: In function 'void construct()':
port_facility.cpp:38:11: warning: unused variable 'q' [-Wunused-variable]
     range q[n]; 
           ^

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