Submission #81901

#	Time	Username	Problem	Language	Result	Execution time	Memory
81901		aquablitz11	Port Facility (JOI17_port_facility)	C++14	0 / 100	183 ms	197568 KiB

port_facility

#include <bits/stdc++.h>
using namespace std;

using pii = pair<int, int>;
#define x first
#define y second

const int N = 1<<20;
const int MOD = 1e9+7;

int n;
pii A[N];
pii ev[N<<1];
int col[N];

set<pii> seg[N<<2];

void add(int i, pii x, int p=1, int b=0, int e=2*n-1) {
    seg[p].insert(x);
    if (b == e)
        return;
    int m = (b+e)/2;
    if (i <= m)
        add(i, x, p<<1, b, m);
    else
        add(i, x, p<<1|1, m+1, e);
}

void remove(int i, pii x, int p=1, int b=0, int e=2*n-1) {
    seg[p].erase(x);
    if (b == e)
        return;
    int m = (b+e)/2;
    if (i <= m)
        remove(i, x, p<<1, b, m);
    else
        remove(i, x, p<<1|1, m+1, e);
}

pii get(int l, int r, int x, int p=1, int b=0, int e=2*n-1) {
    if (l > r || b > e || b > r || e < l)
        return pii(-1, -1);
    if (b >= l && e <= r) {
        auto ptr = seg[p].lower_bound(pii(x, 0));
        return ptr == seg[p].end() ? pii(-1, -1) : *ptr;
    }
    int m = (b+e)/2;
    pii ans = get(l, r, x, p<<1, b, m);
    if (ans != pii(-1, -1))
        return ans;
    ans = get(l, r, x, p<<1|1, m+1, e);
    return ans;
}

bool intersect(int al, int ar, int bl, int br)
{
    if (bl > ar || br < al) return false;
    if (bl >= al && br <= ar) return false;
    if (al >= bl && ar <= br) return false;
    return true;
}

void solve(int i, int lv=0)
{
    remove(A[i].x, pii(A[i].y, i));
    //for (int j = 0; j < lv; ++j)
        //printf("| ");
    //printf("solve %d, color = %d\n", i, col[i]);
    while (true) {
        pii ans = get(A[i].x, A[i].y, A[i].y);
        if (ans == pii(-1, -1))
            ans = get(0, A[i].x-1, A[i].x);
        int j = ans.y;
        if (ans == pii(-1, -1) || !intersect(A[i].x, A[i].y, A[j].x, A[j].y))
            break;
        col[j] = col[i] == 1 ? 2 : 1;
        solve(j, lv+1);
    }
}

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) {
        scanf("%d%d", &A[i].x, &A[i].y);
        ev[--A[i].x] = pii(i, 1);
        ev[--A[i].y] = pii(i, 2);
        add(A[i].x, pii(A[i].y, i));
    }
    int ans = 1;
    for (int i = 0; i < n && ans != 0; ++i) {
        if (!col[i]) {
            col[i] = 1;
            solve(i);
            ans = (ans*2)%MOD;
        }
    }
    stack<int> S[2];
    for (int i = 0; i < 2*n; ++i) {
        int x = ev[i].x, t = ev[i].y;
        int c = col[x]-1;
        if (t == 1)
            S[c].push(x);
        else {
            if (S[c].top() != x) {
                ans = 0;
                break;
            }
            S[c].pop();
        }
    }

    printf("%d\n", ans);

    return 0;
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:83:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
port_facility.cpp:85:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &A[i].x, &A[i].y);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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