Submission #1048020

#	Time	Username	Problem	Language	Result	Execution time	Memory
1048020		sofijavelkovska	Event Hopping (BOI22_events)	C++17	10 / 100	201 ms	17180 KiB

events

#include <bits/stdc++.h>
using namespace std;

const int MAXN=1e5;

int n;
int l[MAXN], r[MAXN];
vector<int> adj[MAXN];
int in[MAXN], out[MAXN], level[MAXN];
int timer=0;

bool compare(int x, int y)
{
    if (r[x]==r[y])
        return l[x]<l[y];

    return r[x]<r[y];
}

void traverse(int x, int k)
{
    level[x]=k;
    timer=timer+1;
    in[x]=timer;
    for (auto y : adj[x])
        traverse(y, k+1);
    out[x]=timer;

    return;
}

bool ancestor(int x, int y)
{
    return in[x]>=in[y] && out[x]<=out[y];
}

int main()
{
    int q;
    cin >> n >> q;
    for (int i=0; i<n; i++)
        cin >> l[i] >> r[i];
    int sorted[n];
    for (int i=0; i<n; i++)
        sorted[i]=i;
    sort(sorted, sorted+n, compare);
    int parent[n];
    for (int i=0; i<n; i++)
        parent[i]=-1;
    int leftmost=sorted[n-1];
    for (int i=n-1; i>=0; i--)
    {
        int x=sorted[i];
        if (l[leftmost]<=r[x] && leftmost!=x)
        {
            parent[x]=leftmost;
            adj[leftmost].push_back(x);
        }
        if (l[x]<l[leftmost])
            leftmost=x;
    }
    for (int i=0; i<n; i++)
        if (parent[i]==-1)
            traverse(i, 0);
    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 << 1 << '\n';
            continue;
        }
        if (ancestor(x, y))
            cout << level[x]-level[y] << '\n';
        else
            cout << "impossible" << '\n';
    }

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30