Submission #748883

#	Time	Username	Problem	Language	Result	Execution time	Memory
748883		GrindMachine	Event Hopping (BOI22_events)	C++17	25 / 100	1592 ms	6572 KiB

events

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

template<typename T>
struct segtree {
    // https://codeforces.com/blog/entry/18051

    /*=======================================================*/

    struct data {
        int a;
    };

    data neutral = {inf1};

    data merge(data &left, data &right) {
        data curr;
        curr.a = min(left.a,right.a);
        return curr;        
    }

    void create(int i, T v) {
        tr[i].a = v;
    }

    void modify(int i, T v) {
        amin(tr[i].a, v);
    }

    /*=======================================================*/

    int n;
    vector<data> tr;

    segtree() {

    }

    segtree(int siz) {
        init(siz);
    }

    void init(int siz) {
        n = siz;
        tr.assign(2 * n, neutral);
    }

    void build(vector<T> &a, int siz) {
        rep(i, siz) create(i + n, a[i]);
        rev(i, n - 1, 1) tr[i] = merge(tr[i << 1], tr[i << 1 | 1]);
    }

    void pupd(int i, T v) {
        modify(i + n, v);
        for (i = (i + n) >> 1; i; i >>= 1) tr[i] = merge(tr[i << 1], tr[i << 1 | 1]);
    }

    data query(int l, int r) {
        data resl = neutral, resr = neutral;

        for (l += n, r += n; l <= r; l >>= 1, r >>= 1) {
            if (l & 1) resl = merge(resl, tr[l++]);
            if (!(r & 1)) resr = merge(tr[r--], resr);
        }

        return merge(resl, resr);
    }
};

void solve(int test_case)
{
    int n,q; cin >> n >> q;
    vector<pii> a(n+5);
    rep1(i,n) cin >> a[i].ff >> a[i].ss;

    vector<int> b;
    rep1(i,n) b.pb(a[i].ff), b.pb(a[i].ss);

    sort(all(b));
    b.resize(unique(all(b))-b.begin());
    int siz = sz(b);

    rep1(i,n){
        a[i].ff = lower_bound(all(b),a[i].ff) - b.begin();
        a[i].ss = lower_bound(all(b),a[i].ss) - b.begin();
    }

    vector<pii> order;
    rep1(i,n) order.pb({a[i].ss, i});
    sort(all(order));

    while(q--){
        int u,v; cin >> u >> v;
        if(u == v){
            cout << 0 << endl;
            conts;
        }
    
        vector<int> dp(n+5,inf1);
        dp[u] = 0;
        segtree<int> st(siz+5);
        st.pupd(a[u].ss, 0);

        for(auto [val, i] : order){
            if(i == u or i == v) conts;
            int best = st.query(a[i].ff, a[i].ss).a;
            dp[i] = best + 1;
            st.pupd(a[i].ss, dp[i]);
        }

        {
            int i = v;
            int best = st.query(a[i].ff, a[i].ss).a;
            dp[i] = best + 1;
            st.pupd(a[i].ss, dp[i]);
        }

        int ans = dp[v];

        if(ans <= n){
            cout << ans << endl;
        }
        else{
            cout << "impossible" << endl;
        }
    }
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30