Submission #1122611

#	Time	Username	Problem	Language	Result	Execution time	Memory
1122611		steveonalex	Event Hopping (BOI22_events)	C++20	100 / 100	116 ms	11856 KiB

events

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()

ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}

ll gcd(ll a, ll b){return __gcd(a, b);}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return __lg(mask);}

mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}

template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }

template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }

template <class T>
    void printArr(T& container, string separator = " ", string finish = "\n"){
        for(auto item: container) cout << item << separator;
        cout << finish;
    }


template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const int INF = 1e9 + 69, LOG_N = 17;

bool isIn(int x, pair<int, int> range){
    return range.first <= x && x <= range.second;
}

struct SegmentTree{
    int n;
    vector<pair<int,int>> a;

    SegmentTree(int _n){
        n = _n;
        a.resize(n * 2 + 2, {INF, -1});
    }

    void update(int i, pair<int, int> v){
        i += n; a[i] = v;
        while(i > 1){
            i >>= 1;
            a[i] = min(a[i * 2], a[i * 2 + 1]);
        }
    }

    pair<int, int> get(int l, int r){
        l += n; r += n + 1;
        pair<int, int> ans = {INF, -1};
        while(l < r){
            if (l & 1) minimize(ans, a[l++]);
            if (r & 1) minimize(ans, a[--r]);
            l >>= 1; r >>= 1;
        }
        return ans;
    }
};

void solve(){
    int n, q;  cin >> n >> q;
    vector<pair<int, int>> a(n);
    for(int i =0; i<n; ++i) cin >> a[i].first >> a[i].second;

    vector<int> x;
    for(pair<int, int> i: a) x.push_back(i.second); 
    remove_dup(x);

    int m = x.size();
    vector<pair<int, int>> best(m, {INF, -1});
    for(int i = 0; i < n; ++i) {
        int idx = lower_bound(ALL(x), a[i].second) - x.begin();
        minimize(best[idx], make_pair(a[i].first, i));
    }

    SegmentTree st(m);
    for(int i = 1; i <= m; ++i) st.update(i, best[i-1]);

    int nxt[LOG_N][n]; memset(nxt, 0, sizeof nxt);
    for(int i = 0; i < n; ++i){
        int l = lower_bound(ALL(x), a[i].first) - x.begin();
        int r = lower_bound(ALL(x), a[i].second) - x.begin();
        nxt[0][i] = st.get(l+1, r+1).second;
    }
    for(int j = 1; j < LOG_N; ++j) for(int i = 0; i < n; ++i) nxt[j][i] = nxt[j-1][nxt[j-1][i]];
    while(q--){
        int u, v; cin >> u >> v;
        u--; v--;
        if (u == v) cout << 0 << "\n";
        else if (a[v].second < a[u].second) cout << "impossible\n";
        else if (isIn(a[u].second, a[v])) cout << 1 << "\n";
        else{
            swap(u, v);
            int ans = 0;
            for(int j = LOG_N - 1; j >= 0; --j){
                int _u = nxt[j][u];
                if (a[_u].first > a[v].second){
                    u = _u;
                    ans += MASK(j);
                }
            }

            if (ans == MASK(LOG_N) - 1) cout << "impossible\n";
            else cout << ans + 2 << "\n";
        }
    }
}

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

    clock_t start = clock();

    solve();

    cerr << "Time elapsed: " << clock() - start << "ms!\n";
    return 0;
}

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