Submission #81965

#	Time	Username	Problem	Language	Result	Execution time	Memory
81965		aquablitz11	Port Facility (JOI17_port_facility)	C++14	0 / 100	169 ms	197496 KiB

port_facility

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

using pii = pair<int, int>;
#define x first
#define y second
#define all(x) x.begin(), x.end()

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

int n;
pii A[N];
pii ev[N<<1], ev2[N<<1];
int col[N];

vector<pii> seg[N<<2], seg2[N<<2];
int ptr[N<<2], ptr2[N<<2];

void build(vector<pii> seg[], int ptr[], pii ev[], int p=1, int b=0, int e=2*n-1)
{
    if (b == e) {
        if (ev[b].y == 1)
            seg[p].push_back(pii(A[ev[b].x].y, ev[b].x));
    } else {
        int m = (b+e)/2;
        build(seg, ptr, ev, p<<1, b, m);
        build(seg, ptr, ev, p<<1|1, m+1, e);
        merge(all(seg[p<<1]), all(seg[p<<1|1]), back_inserter(seg[p]));
    }
    ptr[p] = seg[p].size()-1;
    //printf("node %d [%d,%d]:", p, b, e);
    //for (auto x : seg[p]) printf(" %d", x);
    //printf("\n");
}

pii amort(vector<pii> seg[], int ptr[], int p, int b, int e)
{
    //printf("amortizing %d %d %d\n", p, b, e);
    while (ptr[p] >= 0 && col[seg[p][ptr[p]].y])
        --ptr[p];
    return ptr[p] == -1 ? pii(-1, -1) : seg[p][ptr[p]];
}

pii get(vector<pii> seg[], int ptr[], int l, int r, int p=1, int b=0, int e=2*n-1)
{
    if (b > r || e < l)
        return pii(-1, -1);
    if (b >= l && e <= r)
        return amort(seg, ptr, p, b, e);
    int m = (b+e)/2;
    return max(get(seg, ptr, l, r, p<<1, b, m), get(seg, ptr, l, r, p<<1|1, m+1, e));
}

inline 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)
{
    //printf("solve %d, color = %d\n", i, col[i]);
    bool att = true;
    while (true) {
        pii ans(-1, -1);
        if (att)
            ans = get(seg, ptr, A[i].x, A[i].y);
        if (ans == pii(-1, -1)) {
            att = false;
            ans = get(seg2, ptr2, 2*n-A[i].y-1, 2*n-A[i].x-1);
        }
        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);
    }
}

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);
        //printf("%d: %d %d\n", i, A[i].x, A[i].y);
        int fx = 2*n-A[i].x-1, fy = 2*n-A[i].y-1;
        ev2[fy] = pii(i, 1);
        ev2[fx] = pii(i, 2);
        //printf("%d': %d %d\n", i, fy, fx);
    }
    build(seg, ptr, ev);
    build(seg2, ptr2, ev2);
    int ans = 1;
    for (int i = 0; i < n; ++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:85:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
port_facility.cpp:87:14: 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