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Submission #864167

# Submission time Handle Problem Language Result Execution time Memory
864167 2023-10-22T07:53:34 Z danikoynov Event Hopping (BOI22_events) C++14
10 / 100
 1014 ms 29084 KB 
    #include<bits/stdc++.h>
    #define debug true
    #ifdef DEVAL 
        #define debug false
    #endif
     
    using namespace std;
     
    const int maxn = 1e5 + 10;
     
    struct interval
    {
        int s, e, idx;
    }seg[maxn];
     
    int n, q;   
    pair < int, int > task[maxn];
    void read()
    {
        cin >> n >> q;
        for (int i = 1; i <= n; i ++)
        {
            cin >> seg[i].s >> seg[i].e;
            seg[i].idx = i;
        }
        for (int i = 1; i <= q; i ++)
        {
            cin >> task[i].first >> task[i].second;
        }
    }
     
     
    vector < int > adj[maxn];
     
    int used[maxn], dist[5010][5010];
    int my_queue[maxn];
    void bfs(int start)
    {
        for (int i = 1; i <= n; i ++)
            used[i] = -1;
     
        used[start] = 0;
        int st = 1, en = 0;
        my_queue[++ en]  = start;
        while(st <= en)
        {
            int v = my_queue[st ++];
            for (int u : adj[v])
            {
                if (used[u] == - 1)
                {
                    used[u] = used[v] + 1;
                    my_queue[++ en] = u;
                }
            }
        }
    }
     
    void build_graph()
    {
        for (int i = 1; i <= n; i ++)
           for (int j = 1; j <= n; j ++)
            {
                if (seg[j].s <= seg[i].e && seg[i].e <= seg[j].e)
                    adj[i].push_back(j);
            }
    }
     
    void answer_queries()
    {
        for (int i = 1; i <= q; i ++)
        {
            if (dist[task[i].first][task[i].second] == -1)
                cout << "impossible" << endl;
            else
                cout << dist[task[i].first][task[i].second] << endl;
     
        }
    }
     
    void precalc()
    {
        for (int v = 1; v <= n; v ++)
        {
            bfs(v);
            for (int i = 1; i <= n; i ++)
                dist[v][i] = used[i];
        }
    }
     
    void speed()
    {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);
    }
    
    bool cmp(interval seg1, interval seg2)
    {
        return seg1.s < seg2.s;
    }

    const int maxlog = 21;

    int dp[maxlog][maxn], rev[maxn];
    void solve_no_intersect()
    {
        sort(seg + 1, seg + n + 1, cmp);
        int pt = n;
        for (int i = n; i > 0; i --)
        {
            while(seg[pt].s > seg[i].e)
                pt --;
            dp[0][i] = pt;
        }

        for (int j = 1; j < maxlog; j ++)
            for (int i = 1; i <= n; i ++)
            {
                dp[j][i] = dp[j - 1][dp[j - 1][i]];
            }

        for (int i = 1; i <= n; i ++)
            rev[seg[i].idx] = i;
        for (int i = 1; i <= q; i ++)
        {
            int S = task[i].first, E = task[i].second;
            S = rev[S];
            E = rev[E];
            if (S > E)
            {
                cout << "impossible" << endl;
                continue;
            }

            if (S == E)
            {
                cout << 0 << endl;
                continue;
            }
        
            int jump = 0;
            for (int bit = maxlog - 1; bit >= 0; bit --)
            {
                if (dp[bit][S] < E)
                {
                    jump |= (1 << bit);
                    S = dp[bit][S];
                }
            }

            if (dp[0][S] != E)
                cout << "impossible" << endl;
            else
                cout << jump + 1 << endl;
        }

    }
    void solve()
    {
     
        read();
        if (n > 1000 || q > 100)
        {
            solve_no_intersect();
        }  
        else
        {
            build_graph();
            precalc();
            answer_queries(); 
        }   
    }
     
    int main()
    {
        speed();
        solve();
        return 0;
    }
    /**
        3 2
        1 2
        2 3
        3 4
        1 3
        2 3
    */

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6488 KB Output is correct
2 Correct 161 ms 16520 KB Output is correct
3 Correct 154 ms 19592 KB Output is correct
4 Correct 169 ms 19592 KB Output is correct
5 Incorrect 153 ms 20056 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6492 KB Output is correct
2 Correct 1 ms 6492 KB Output is correct
3 Correct 13 ms 25104 KB Output is correct
4 Correct 10 ms 25064 KB Output is correct
5 Correct 13 ms 24924 KB Output is correct
6 Correct 55 ms 25876 KB Output is correct
7 Correct 160 ms 26668 KB Output is correct
8 Correct 175 ms 27712 KB Output is correct
9 Correct 972 ms 29064 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6492 KB Output is correct
2 Correct 1 ms 6492 KB Output is correct
3 Correct 13 ms 25104 KB Output is correct
4 Correct 10 ms 25064 KB Output is correct
5 Correct 13 ms 24924 KB Output is correct
6 Correct 55 ms 25876 KB Output is correct
7 Correct 160 ms 26668 KB Output is correct
8 Correct 175 ms 27712 KB Output is correct
9 Correct 972 ms 29064 KB Output is correct
10 Correct 1 ms 6492 KB Output is correct
11 Correct 1 ms 6488 KB Output is correct
12 Correct 17 ms 24924 KB Output is correct
13 Correct 11 ms 24924 KB Output is correct
14 Correct 13 ms 24924 KB Output is correct
15 Correct 50 ms 25684 KB Output is correct
16 Correct 149 ms 26664 KB Output is correct
17 Correct 180 ms 27724 KB Output is correct
18 Correct 982 ms 29084 KB Output is correct
19 Incorrect 125 ms 13816 KB Output isn't correct
20 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6492 KB Output is correct
2 Correct 1 ms 6492 KB Output is correct
3 Correct 13 ms 25104 KB Output is correct
4 Correct 10 ms 25064 KB Output is correct
5 Correct 13 ms 24924 KB Output is correct
6 Correct 55 ms 25876 KB Output is correct
7 Correct 160 ms 26668 KB Output is correct
8 Correct 175 ms 27712 KB Output is correct
9 Correct 972 ms 29064 KB Output is correct
10 Correct 1 ms 6488 KB Output is correct
11 Correct 1 ms 6492 KB Output is correct
12 Correct 18 ms 24924 KB Output is correct
13 Correct 10 ms 25176 KB Output is correct
14 Correct 13 ms 24920 KB Output is correct
15 Correct 49 ms 25872 KB Output is correct
16 Correct 150 ms 26452 KB Output is correct
17 Correct 176 ms 27736 KB Output is correct
18 Correct 1014 ms 29060 KB Output is correct
19 Correct 31 ms 15960 KB Output is correct
20 Correct 25 ms 16976 KB Output is correct
21 Incorrect 30 ms 17612 KB Output isn't correct
22 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 150 ms 16520 KB Output is correct
2 Correct 150 ms 19612 KB Output is correct
3 Correct 160 ms 19624 KB Output is correct
4 Correct 151 ms 19936 KB Output is correct
5 Correct 165 ms 19792 KB Output is correct
6 Incorrect 172 ms 20040 KB Output isn't correct
7 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6488 KB Output is correct
2 Correct 161 ms 16520 KB Output is correct
3 Correct 154 ms 19592 KB Output is correct
4 Correct 169 ms 19592 KB Output is correct
5 Incorrect 153 ms 20056 KB Output isn't correct
6 Halted 0 ms 0 KB -