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Submission #1048085

# Submission time Handle Problem Language Result Execution time Memory
1048085 2024-08-07T22:04:33 Z sofijavelkovska Event Hopping (BOI22_events) C++17
0 / 100
 107 ms 12492 KB 
#include <bits/stdc++.h>
using namespace std;

const int MAXN=(1<<18), LOG=17, INF=1e9;

int tree[2*MAXN-1];

int find(int x, int l, int r, int lt, int rt)
{
    if (l>=rt || r<=lt)
        return INF;
    if (l>=lt && r<=rt)
        return tree[x];

    return min(find(2*x+1, l, (l+r)/2, lt, rt), find(2*x+2, (l+r)/2, r, lt, rt));
}

void update(int x, int l, int r, int index, int value)
{
    if (l>index || r<=index)
        return;
    if (r-l==1)
    {
        tree[x]=min(tree[x], value);
        return;
    }
    update(2*x+1, l, (l+r)/2, index, value);
    update(2*x+2, (l+r)/2, r, index, value);
    tree[x]=min(tree[2*x+1], tree[2*x+2]);

    return;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, q;
    cin >> n >> q;
    int l[n], r[n];
    for (int i=0; i<n; i++)
        cin >> l[i] >> r[i];
    vector<int> temp;
    for (int i=0; i<n; i++)
    {
        temp.push_back(l[i]);
        temp.push_back(r[i]);
    }
    sort(temp.begin(), temp.end());
    vector<int> compress;
    for (auto x : temp)
        if (compress.empty() || x!=compress.back())
            compress.push_back(x);
    for (int i=0; i<2*MAXN-1; i++)
        tree[i]=INF;
    for (int i=0; i<n; i++)
    {
        int leftindex=lower_bound(compress.begin(), compress.end(), l[i])-compress.begin();
        int rightindex=lower_bound(compress.begin(), compress.end(), r[i])-compress.begin();
        update(0, 0, MAXN, rightindex, leftindex);
    }
    int prev[compress.size()];
    for (int i=0; i<compress.size(); i++)
        prev[i]=-1;
    for (int i=0; i<n; i++)
    {
        int leftindex=lower_bound(compress.begin(), compress.end(), l[i])-compress.begin();
        int rightindex=lower_bound(compress.begin(), compress.end(), r[i])-compress.begin();
        prev[leftindex]=find(0, 0, MAXN, leftindex, rightindex+1);
        if (prev[leftindex]==leftindex)
            prev[leftindex]=-1;
    }
    int blift[compress.size()][LOG];
    for (int i=0; i<compress.size(); i++)
        for (int j=0; j<LOG; j++)
            blift[i][j]=-1;
    for (int i=0; i<compress.size(); i++)
        blift[i][0]=prev[i];
    for (int j=1; j<LOG; j++)
        for (int i=0; i<compress.size(); i++)
            if (blift[i][j-1]!=-1)
                blift[i][j]=blift[blift[i][j-1]][j-1];
    /*for (int j=0; j<3; j++)
    {
        for (int i=0; i<compress.size(); i++)
            cout << blift[i][j] << ' ';
        cout << '\n';
    }*/
    while (q--)
    {
        int x, y;
        cin >> x >> y;
        x=x-1;
        y=y-1;
        if (x==y)
        {
            cout << 0 << '\n';
            continue;
        }
        if (r[x]>r[y])
        {
            cout << "impossible" << '\n';
            continue;
        }
        int total=1;
        int i=lower_bound(compress.begin(), compress.end(), l[y])-compress.begin();
        //cout << "x y " << x+1 << ' ' << y+1 << '\n';
        //cout << "i " << compress[i] << '\n';
        for (int j=LOG-1; j>=0; j--)
            if (blift[i][j]!=-1 && compress[blift[i][j]]>r[x])
            {
                i=blift[i][j];
                //cout << "i " << compress[i] << '\n';
                total=total+(1<<j);
            }
        if (blift[i][0]!=-1 && compress[blift[i][0]]<=r[x])
            cout << total+1 << '\n';
        else
            cout << "impossible" << '\n';
    }

    return 0;
}

Compilation message

events.cpp: In function 'int main()':
events.cpp:64:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |     for (int i=0; i<compress.size(); i++)
      |                   ~^~~~~~~~~~~~~~~~
events.cpp:75:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   75 |     for (int i=0; i<compress.size(); i++)
      |                   ~^~~~~~~~~~~~~~~~
events.cpp:78:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |     for (int i=0; i<compress.size(); i++)
      |                   ~^~~~~~~~~~~~~~~~
events.cpp:81:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   81 |         for (int i=0; i<compress.size(); i++)
      |                       ~^~~~~~~~~~~~~~~~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2396 KB Output is correct
2 Correct 98 ms 12408 KB Output is correct
3 Correct 106 ms 12492 KB Output is correct
4 Incorrect 105 ms 12492 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2392 KB Output is correct
2 Correct 1 ms 2396 KB Output is correct
3 Correct 1 ms 2396 KB Output is correct
4 Incorrect 2 ms 2396 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2392 KB Output is correct
2 Correct 1 ms 2396 KB Output is correct
3 Correct 1 ms 2396 KB Output is correct
4 Incorrect 2 ms 2396 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2392 KB Output is correct
2 Correct 1 ms 2396 KB Output is correct
3 Correct 1 ms 2396 KB Output is correct
4 Incorrect 2 ms 2396 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 107 ms 12492 KB Output is correct
2 Correct 103 ms 12492 KB Output is correct
3 Incorrect 104 ms 12488 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2396 KB Output is correct
2 Correct 98 ms 12408 KB Output is correct
3 Correct 106 ms 12492 KB Output is correct
4 Incorrect 105 ms 12492 KB Output isn't correct
5 Halted 0 ms 0 KB -