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Submission #864250

# Submission time Handle Problem Language Result Execution time Memory
864250 2023-10-22T09:26:00 Z danikoynov Event Hopping (BOI22_events) C++14
25 / 100
 1500 ms 9960 KB 
#include<bits/stdc++.h>

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 input()
{
    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;
    }
}


bool cmp_end(interval seg1, interval seg2)
{
    
    return seg1.e < seg2.e;
}

int lf[maxn], rev[maxn], rf[maxn];
map < int, int > fix;
void build_graph()
{
    sort(seg + 1, seg + n + 1, cmp_end);
    for (int i = 1; i <= n; i ++)
    {
        rev[seg[i].idx] = i;
    }

    for (int i = 1; i <= n; i ++)
    {
        int l = 1;
        int r = i;
        while(l <= r)
        {
            int m = (l + r) / 2;
            if (seg[m].e < seg[i].s)
                l = m + 1;
            else
                r = m - 1;
        }
        lf[i] = l;
        //while(seg[lf[i]].e < seg[i].s)
           // lf[i] ++;


        if (fix[seg[i].e] == 0)
            fix[seg[i].e] = lf[i];
        else
            fix[seg[i].e] = min(fix[seg[i].e], lf[i]);
    }
}

void answer_queries()
{
    /**cout << "----------------------" << endl;
    for (int i = 1; i <= n; i ++)
        cout << seg[i].s << " :: " << seg[i].e << endl;*/
    
    for (int i = 1; i <= q; i ++)
    {
        int st = rev[task[i].first], en = rev[task[i].second];

        if (seg[st].e == seg[en].e && st != en)
        {
            cout << 1 << endl;
            continue;
        }
        if (st > en)
        {
            cout << "impossible" << endl;
            continue;
        }
        int steps = 0, last_left = en + 1;
        int bound_left = en;
        bool done = false;
        while(!(st >= bound_left))
        {
            ///cout << last_left << " " << bound_left << endl;
            steps ++;
            int new_left = bound_left;
            for (int i = bound_left; i < last_left; i ++)
            {
                new_left = min(new_left, lf[i]);
            }
            ///cout << "here " << lf[en] << " " << fix[seg[en].e] << " " << seg[en].s << endl;
            if (steps == 2)
                new_left = min(new_left, fix[seg[en].e]);
            ///cout << new_bound << endl;
            if (new_left == bound_left && steps > 1)
            {
                done = true;
                break;
            }
            
            last_left = bound_left;
            bound_left = new_left;
        }

        if (done)
            cout << "impossible" << endl;
        else
            cout << steps << endl;
    }
}
void solve()
{  
    input();
    build_graph();
    answer_queries();
}

int main()
{   
    ///speed();
    solve();

    return 0;
}

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2396 KB Output is correct
2 Execution timed out 1582 ms 7936 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2396 KB Output is correct
2 Correct 0 ms 2396 KB Output is correct
3 Correct 2 ms 2396 KB Output is correct
4 Correct 2 ms 2396 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2396 KB Output is correct
7 Correct 2 ms 2392 KB Output is correct
8 Correct 1 ms 2396 KB Output is correct
9 Correct 1 ms 2396 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2396 KB Output is correct
2 Correct 0 ms 2396 KB Output is correct
3 Correct 2 ms 2396 KB Output is correct
4 Correct 2 ms 2396 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2396 KB Output is correct
7 Correct 2 ms 2392 KB Output is correct
8 Correct 1 ms 2396 KB Output is correct
9 Correct 1 ms 2396 KB Output is correct
10 Correct 0 ms 2392 KB Output is correct
11 Correct 0 ms 2392 KB Output is correct
12 Correct 2 ms 2396 KB Output is correct
13 Correct 1 ms 2396 KB Output is correct
14 Correct 1 ms 2392 KB Output is correct
15 Correct 1 ms 2396 KB Output is correct
16 Correct 2 ms 2396 KB Output is correct
17 Correct 1 ms 2396 KB Output is correct
18 Correct 1 ms 2648 KB Output is correct
19 Correct 920 ms 3044 KB Output is correct
20 Execution timed out 1563 ms 3156 KB Time limit exceeded
21 Halted 0 ms 0 KB -

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2396 KB Output is correct
2 Correct 0 ms 2396 KB Output is correct
3 Correct 2 ms 2396 KB Output is correct
4 Correct 2 ms 2396 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2396 KB Output is correct
7 Correct 2 ms 2392 KB Output is correct
8 Correct 1 ms 2396 KB Output is correct
9 Correct 1 ms 2396 KB Output is correct
10 Correct 0 ms 2396 KB Output is correct
11 Correct 0 ms 2396 KB Output is correct
12 Correct 2 ms 2396 KB Output is correct
13 Correct 1 ms 2396 KB Output is correct
14 Correct 1 ms 2396 KB Output is correct
15 Correct 1 ms 2396 KB Output is correct
16 Correct 1 ms 2396 KB Output is correct
17 Correct 1 ms 2396 KB Output is correct
18 Correct 1 ms 2396 KB Output is correct
19 Correct 115 ms 7972 KB Output is correct
20 Correct 76 ms 9044 KB Output is correct
21 Correct 83 ms 7288 KB Output is correct
22 Correct 87 ms 9780 KB Output is correct
23 Correct 88 ms 9960 KB Output is correct
24 Correct 95 ms 9908 KB Output is correct
25 Correct 51 ms 4444 KB Output is correct

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1552 ms 8276 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2396 KB Output is correct
2 Execution timed out 1582 ms 7936 KB Time limit exceeded
3 Halted 0 ms 0 KB -