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Submission #864171

# Submission time Handle Problem Language Result Execution time Memory
864171 2023-10-22T07:56:17 Z danikoynov Event Hopping (BOI22_events) C++14
30 / 100
 1063 ms 29332 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 6492 KB Output is correct
2 Correct 183 ms 16412 KB Output is correct
3 Correct 158 ms 16308 KB Output is correct
4 Correct 154 ms 16468 KB Output is correct
5 Incorrect 148 ms 16976 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 25096 KB Output is correct
4 Correct 10 ms 24924 KB Output is correct
5 Correct 14 ms 24920 KB Output is correct
6 Correct 48 ms 25680 KB Output is correct
7 Correct 141 ms 26668 KB Output is correct
8 Correct 221 ms 27732 KB Output is correct
9 Correct 939 ms 29068 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 25096 KB Output is correct
4 Correct 10 ms 24924 KB Output is correct
5 Correct 14 ms 24920 KB Output is correct
6 Correct 48 ms 25680 KB Output is correct
7 Correct 141 ms 26668 KB Output is correct
8 Correct 221 ms 27732 KB Output is correct
9 Correct 939 ms 29068 KB Output is correct
10 Correct 1 ms 6492 KB Output is correct
11 Correct 1 ms 6488 KB Output is correct
12 Correct 12 ms 24924 KB Output is correct
13 Correct 10 ms 25100 KB Output is correct
14 Correct 12 ms 24920 KB Output is correct
15 Correct 48 ms 25628 KB Output is correct
16 Correct 145 ms 26672 KB Output is correct
17 Correct 173 ms 27732 KB Output is correct
18 Correct 1063 ms 29332 KB Output is correct
19 Correct 126 ms 13080 KB Output is correct
20 Correct 124 ms 14168 KB Output is correct
21 Incorrect 132 ms 14428 KB Output isn't correct
22 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 25096 KB Output is correct
4 Correct 10 ms 24924 KB Output is correct
5 Correct 14 ms 24920 KB Output is correct
6 Correct 48 ms 25680 KB Output is correct
7 Correct 141 ms 26668 KB Output is correct
8 Correct 221 ms 27732 KB Output is correct
9 Correct 939 ms 29068 KB Output is correct
10 Correct 1 ms 6488 KB Output is correct
11 Correct 1 ms 6492 KB Output is correct
12 Correct 13 ms 24924 KB Output is correct
13 Correct 10 ms 24924 KB Output is correct
14 Correct 13 ms 25096 KB Output is correct
15 Correct 47 ms 25876 KB Output is correct
16 Correct 145 ms 26968 KB Output is correct
17 Correct 169 ms 27736 KB Output is correct
18 Correct 971 ms 29328 KB Output is correct
19 Correct 27 ms 15708 KB Output is correct
20 Correct 23 ms 15704 KB Output is correct
21 Incorrect 27 ms 15708 KB Output isn't correct
22 Halted 0 ms 0 KB -

Subtask #5
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 152 ms 16308 KB Output is correct
2 Correct 149 ms 16468 KB Output is correct
3 Correct 172 ms 16304 KB Output is correct
4 Correct 155 ms 16980 KB Output is correct
5 Correct 152 ms 16724 KB Output is correct
6 Correct 155 ms 16436 KB Output is correct
7 Correct 159 ms 16420 KB Output is correct
8 Correct 160 ms 16976 KB Output is correct
9 Correct 29 ms 15760 KB Output is correct
10 Correct 148 ms 16208 KB Output is correct
11 Correct 153 ms 16296 KB Output is correct
12 Correct 153 ms 16364 KB Output is correct

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 6492 KB Output is correct
2 Correct 183 ms 16412 KB Output is correct
3 Correct 158 ms 16308 KB Output is correct
4 Correct 154 ms 16468 KB Output is correct
5 Incorrect 148 ms 16976 KB Output isn't correct
6 Halted 0 ms 0 KB -