Submission #69133

#	Time	Username	Problem	Language	Result	Execution time	Memory
69133		Inovak	Port Facility (JOI17_port_facility)	C++14	0 / 100	3 ms	376 KiB

port_facility

#include <bits/stdc++.h>

#define fr first
#define sc second
#define pb push_back
#define mk make_pair
#define ll long long
#define OK puts("OK");
#define sz(s) (int)s.size()
#define all(s) s.begin(), s.end()

using namespace std;

const int N = 2e6+10;
const int mod = 1e9+7;

int n;
pair <int, int> p[N];
stack <int> a, b;
ll ans = 1;

bool go (stack <int> a, stack <int> b, int k) {
    for(int i = k; i <= n; i++) {
        while(a.top() < p[i].fr) a.pop();
        while(b.top() < p[i].fr) b.pop();
        if(a.top() < b.top()) {
            if(a.top() > p[i].sc) a.push(p[i].sc);
            else if(b.top() > p[i].sc) b.push(p[i].sc);
            else return 0;
        }
        else {
            if(b.top() > p[i].sc) b.push(p[i].sc);
            else if(a.top() > p[i].sc) a.push(p[i].sc);
            else return 0;
        }
    }
    return 1;
}

int main() {
    scanf("%d", &n);
    for(int i = 1; i <= n; i++) {
        scanf("%d%d", &p[i].fr, &p[i].sc);
    }
    a.push(mod);
    b.push(mod);
    sort(p + 1, p + n + 1);
    for(int i = 1; i <= n; i++) {
        while(a.top() < p[i].fr) a.pop();
        while(b.top() < p[i].fr) b.pop();
        ll y = 0;

        if(a.top() > p[i].sc) {
            a.push(p[i].sc);
            if(go(a, b, i + 1))
                y += 1;
            a.pop();
        }

        if(b.top() > p[i].sc) {
            b.push(p[i].sc);
            if(go(a, b, i + 1))
                y += 2;
            b.pop();
        }
        if(y == 3) {
            ans = ans * 2ll % mod;
            if(a.top() < b.top()) a.push(p[i].sc);
            else b.push(p[i].sc);
        }
        else if(y) {
            if(y == 1) a.push(p[i].sc);
            else b.push(p[i].sc);
        }
        else {
            puts("0");
            return 0;
        }
    }
    cout << ans << endl;
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:41:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
port_facility.cpp:43:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &p[i].fr, &p[i].sc);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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