제출 #1335903

#제출 시각아이디문제언어결과실행 시간메모리
1335903hoangtien69Event Hopping (BOI22_events)C++20
0 / 100
114 ms13288 KiB
#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
const int MAXN = 1e5 + 5;
const int INF = 1e9 + 10;
const int LOG = 20;

int n, q;
int l[MAXN], r[MAXN];
vector<int> peal;
pii st[4 * MAXN];
int sz = 0;
int jump[MAXN][LOG];

int get(int x)
{
    return lower_bound(peal.begin(), peal.end(), x) - peal.begin() + 1;
}
void build(int id, int l, int r)
{
    if (l == r)
    {
        st[id] = {INF, INF};
        return;
    }
    int m = (l + r) >> 1;
    build(id << 1, l, m);
    build(id << 1 | 1, m + 1, r);
    st[id] = min(st[id << 1], st[id << 1 | 1]);
}
void update(int id, int l, int r, int pos, int val1, int val2)
{
    if (l == r)
    {
        st[id] = min(st[id], {val1, val2});
        return;
    }
    int m = (l + r) >> 1;
    if (pos <= m)
    {
        update(id << 1, l, m, pos, val1, val2);
    }
    else
    {
        update(id << 1 | 1, m + 1, r, pos, val1, val2);
    }
    st[id] = min(st[id << 1], st[id << 1 | 1]);
}
pii query(int id, int l, int r, int u, int v)
{
    if (r < u || v < l)
    {
        return {INF, INF};
    }
    if (u <= l and r <= v)
    {
        return st[id];
    }
    int m = (l + r) >> 1;
    return min(query(id << 1, l, m, u, v), query(id << 1 | 1, m + 1, r, u, v));
}
int solve(int x, int y)
{
    if (x == y)
    {
        return 0;
    }
    if (l[y] <= r[x] and r[x] <= r[y])
    {
        return 1;
    }
    int ans = 2;
    for (int j = LOG - 1; j >= 0; j--)
    {
        if (r[x] < l[jump[y][j]])
        {
            ans += (1 << j);
            y = jump[y][j];
        }
    }
    y = jump[y][0];
    if (r[x] < l[y] || r[x] > r[y])
    {
        return -1;
    }
    return ans;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> q;
    for (int i = 1; i <= n; i++)
    {
        cin >> l[i] >> r[i];
    }
    for (int i = 1; i <= n; i++)
    {
        peal.push_back(r[i]);
    }
    sort(peal.begin(), peal.end());
    peal.erase(unique(peal.begin(), peal.end()), peal.end());
    sz = peal.size();
    build(1, 1, sz);
    for (int i = 1; i <= n; i++)
    {
        int pos = get(r[i]);
        update(1, 1, sz, pos, l[i], i);
    }
    for (int i = 1; i <= n; i++)
    {
        int left = lower_bound(peal.begin(), peal.end(), l[i]) - peal.begin() + 1;
        int right = lower_bound(peal.begin(), peal.end(), r[i]) - peal.begin() + 1;
        pii cak = query(1, 1, sz, left, right);
        jump[i][0] = cak.second;
    }
    for (int j = 1; j < LOG; j++)
    {
        for (int i = 1; i <= n; i++)
        {
            jump[i][j] = jump[jump[i][j - 1]][j - 1];
        }
    }
    for (int i = 1; i <= n; i++)
    {
        cout << i << " " << jump[i][0] << "\n";
    }
    while(q--)
    {
        int x, y;
        cin >> x >> y;
        int ans = solve(x, y);
        if (ans == -1)
        {
            cout << "impossible" << "\n";
        }
        else
        {
            cout << ans << "\n";
        }
    }
}
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