Submission #721886

#	Time	Username	Problem	Language	Result	Execution time	Memory
721886		MDSPro	Event Hopping (BOI22_events)	C++14	0 / 100	55 ms	3912 KiB

events

#include "bits/stdc++.h"
 
using namespace std;
 
struct DSU{
    int n;
    vector<int> par,r;
    DSU(int sz):n(sz){
        par.resize(n); iota(par.begin(),par.end(),0);
        r.assign(n,1);
    }

    int get(int x){
        return par[x] = (x == par[x] ? x : get(par[x]));
    }

    void unite(int a, int b){
        a = get(a);
        b = get(b);
        if(a == b) return;
        if(r[a] > r[b]) swap(a,b);
        r[b] += r[a]; par[a] = b; r[a] = 0;
    }
};

int main(){
    cin.tie(0)->sync_with_stdio(0);
 
    int n,q; cin >> n >> q;
    vector<tuple<int,int,int>> ev;
    for(int i = 0; i < n; ++i){
        int x,y; cin >> x >> y;
        ev.emplace_back(y,x,i+1);
    }
 
    sort(ev.begin(),ev.end());
 
    vector<int> nw_order(n+1);
    vector<int> left(n),right(n);
    for(int i = 0; i < n; ++i) {
        left[i] = get<1>(ev[i]);
        right[i] = get<0>(ev[i]);
        nw_order[get<2>(ev[i])] = i;
    }
    
    DSU dsu(n);
    for(int i = 0; i < n; ++i){
        for(int j = max(0,i-1); j < min(n,i+2); ++j){
            if(i == j) continue;
            if(left[j] <= right[i] && right[i] <= right[j]) dsu.unite(i,j);
        }
    }

    while(q--){
        int a,b; cin >> a >> b;
        a = nw_order[a];
        b = nw_order[b];

        if(left[b] <= right[a] && right[a] <= right[b]) cout << 1;
        else if(dsu.get(a) == dsu.get(b)) cout << b-a;
        else cout << "impossible";
    }
}

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