Submission #834056

#	Time	Username	Problem	Language	Result	Execution time	Memory
834056		LucaIlie	Port Facility (JOI17_port_facility)	C++17	0 / 100	29 ms	62932 KiB

port_facility

#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 1e6;
const int INF = 1e9;
const int MOD = 1e9 + 7;

int n;
bool vis[MAX_N], side[MAX_N];
int l[MAX_N], r[MAX_N];
int indexL[2 * MAX_N + 1], indexR[2 * MAX_N + 1];

struct SEG_TREE {
    int segTree[4 * MAX_N];

    void init() {
        for ( int v = 0; v < 4 * MAX_N; v++ )
            segTree[v] = -INF;
    }

    void update( int v, int l, int r, int pos, int x ) {
        if ( l > pos || r < pos )
            return;

        if ( l == r ) {
            segTree[v] = x;
            return;
        }

        int mid = (l + r) / 2;
        update( v * 2 + 1, l, mid, pos, x );
        update( v * 2 + 2, mid + 1, r, pos, x );
        segTree[v] = max( segTree[v * 2 + 1], segTree[v * 2 + 2] );
    }

    int query( int v, int l, int r, int lq, int rq ) {
        if ( l > rq || r < lq )
            return -INF;

        if ( lq <= l && r <= rq )
            return segTree[v];

        int mid = (l + r) / 2;
        return max( query( v * 2 + 1, l, mid, lq, rq ), query( v * 2 + 2, mid + 1, r, lq, rq ) );
    }
};

SEG_TREE unvisitedByL, unvisitedByR, visitedByL, visitedByR;

void checkBipartit( int u ) {
    vis[u] = true;
    unvisitedByL.update( 0, 1, 2 * n, l[u], -INF );
    unvisitedByR.update( 0, 1, 2 * n, r[u], -INF );

    int rr = unvisitedByL.query( 0, 1, 2 * n, l[u], r[u] );
    while ( rr > r[u] ) {
        int v = indexR[rr];
        side[v] = side[u] ^ 1;
        checkBipartit( v );
        rr = unvisitedByL.query( 0, 1, 2 * n, l[u], r[u] );
    }
    int ll = -unvisitedByR.query( 0, 1, 2 * n, l[u], r[u] );
    while ( ll < l[u] ) {
        int v = indexL[ll];
        side[v] = side[u] ^ 1;
        checkBipartit( v );
        ll = -unvisitedByR.query( 0, 1, 2 * n, l[u], r[u] );
    }
}

int main() {
    cin.tie( NULL );
    cout.tie( NULL );
    ios_base::sync_with_stdio( false );

    cin >> n;
    for ( int i = 0; i < n; i++ )
        cin >> l[i] >> r[i];

    unvisitedByL.init();
    unvisitedByR.init();
    for ( int i = 0; i < n; i++ ) {
        unvisitedByL.update( 0, 1, 2 * n, l[i], r[i] );
        unvisitedByR.update( 0, 1, 2 * n, r[i], -l[i] );
        indexL[l[i]] = i;
        indexR[r[i]] = i;
    }

    int comp = 0;
    for ( int u = 0; u < n; u++ ) {
        if ( !vis[u] ) {
            side[u] = 0;
            checkBipartit( u );
            comp++;
        }
    }

    bool bipartit = true;
    visitedByL.init();
    visitedByR.init();
    for ( int i = 0; i < n; i++ ) {
        if ( side[i] == 1 )
            continue;
        if ( visitedByL.query( 0, 1, 2 * n, l[i], r[i] ) > r[i] )
            bipartit = false;
        if ( visitedByR.query( 0, 1, 2 * n, l[i], r[i] ) < l[i] )
            bipartit = false;
    }
    visitedByL.init();
    visitedByR.init();
    for ( int i = 0; i < n; i++ ) {
        if ( side[i] == 0 )
            continue;
        if ( visitedByL.query( 0, 1, 2 * n, l[i], r[i] ) > r[i] )
            bipartit = false;
        if ( visitedByR.query( 0, 1, 2 * n, l[i], r[i] ) < l[i] )
            bipartit = false;
    }

    if ( bipartit ) {
        int ans = 1;
        for ( int i = 0; i < comp; i++ )
            ans = ans * 2 % MOD;
        cout << ans;
    } else
        cout << 0;

    return 0;
}

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