oj.uz

Submission #604475

# Submission time Handle Problem Language Result Execution time Memory
604475 2022-07-25T06:51:02 Z Jomnoi Event Hopping (BOI22_events) C++17
0 / 100
 162 ms 16308 KB 
#include <bits/stdc++.h>
using namespace std;

const int MAX_N = 1e5 + 5;
const int MAX_M = 5005;
const int INF = 1e9 + 7;

int S[MAX_N], E[MAX_N];
int dist[MAX_N];
int can_reach[MAX_M][MAX_M];
vector <int> graph[MAX_N];
int nxt[MAX_N][20];

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int N, Q;
    cin >> N >> Q;

    for(int i = 1; i <= N; i++) {
        cin >> S[i] >> E[i];
    }

    if(N <= 1000 and Q <= 100 and false) {
        for(int i = 1; i <= N; i++) {
            for(int j = 1; j <= N; j++) {
                if(i != j and S[j] <= E[i] and E[i] <= E[j]) {
                    graph[i].push_back(j);
                }
            }
        }

        for(int i = 1; i <= N; i++) {
            for(int j = 1; j <= N; j++) {
                dist[j] = -1;
            }

            queue <int> q;
            q.push(i);
            dist[i] = 0;
            while(!q.empty()) {
                int u = q.front();
                q.pop();

                for(auto v : graph[u]) {
                    if(dist[v] == -1) {
                        dist[v] = dist[u] + 1;
                        q.push(v);
                    }
                }
            }

            for(int j = 1; j <= N; j++) {
                can_reach[i][j] = dist[j];
            }
        }

        while(Q--) {
            int s, e;
            cin >> s >> e;

            if(can_reach[s][e] == -1) {
                cout << "impossible\n";
            }
            else {
                cout << can_reach[s][e] << '\n';
            }
        }
    }
    else {
        vector <pair <int, int>> vec;
        for(int i = 1; i <= N; i++) {
            vec.emplace_back(E[i], S[i]);
        }

        sort(vec.begin(), vec.end());

        for(int l = 0, r = 0; l < N; l++) {
            while(r < N and l >= r) {
                r++;
            }
            while(r < N and vec[l].first < vec[r].second) {
                r++;
            }

            nxt[l][0] = N;
            if(r < N) {
                nxt[l][0] = r;
            }
        }
        nxt[N][0] = N;
        for(int j = 1; j < 20; j++) {
            for(int i = 0; i <= N; i++) {
                nxt[i][j] = nxt[nxt[i][j - 1]][j - 1];
            }
        }

        while(Q--) {
            int s, e;
            cin >> s >> e;

            int ps = lower_bound(vec.begin(), vec.end(), make_pair(E[s], S[s])) - vec.begin();
            int pe = lower_bound(vec.begin(), vec.end(), make_pair(E[e], S[e])) - vec.begin();

            int ans = 0;
            for(int i = 19; i >= 0; i--) {
                if(nxt[ps][i] <= pe) {
                    ps = nxt[ps][i];
                    ans += (1<<i);
                }
            }
        
            if(ps == pe) {
                cout << ans << '\n';
            }
            else {
                cout << "impossible\n";
            }
        }
    }
    return 0;
}

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 84 ms 13772 KB Output is correct
3 Correct 110 ms 15792 KB Output is correct
4 Correct 106 ms 15776 KB Output is correct
5 Correct 89 ms 15828 KB Output is correct
6 Correct 90 ms 15896 KB Output is correct
7 Correct 100 ms 15968 KB Output is correct
8 Correct 95 ms 16308 KB Output is correct
9 Correct 97 ms 16264 KB Output is correct
10 Incorrect 124 ms 16296 KB Output isn't correct
11 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 2644 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 2644 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 2644 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 108 ms 14248 KB Output is correct
2 Correct 119 ms 14028 KB Output is correct
3 Correct 118 ms 14036 KB Output is correct
4 Correct 81 ms 14632 KB Output is correct
5 Incorrect 162 ms 14500 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 84 ms 13772 KB Output is correct
3 Correct 110 ms 15792 KB Output is correct
4 Correct 106 ms 15776 KB Output is correct
5 Correct 89 ms 15828 KB Output is correct
6 Correct 90 ms 15896 KB Output is correct
7 Correct 100 ms 15968 KB Output is correct
8 Correct 95 ms 16308 KB Output is correct
9 Correct 97 ms 16264 KB Output is correct
10 Incorrect 124 ms 16296 KB Output isn't correct
11 Halted 0 ms 0 KB -