oj.uz

Submission #697955

# Submission time Handle Problem Language Result Execution time Memory
697955 2023-02-11T15:10:03 Z Neos Event Hopping (BOI22_events) C++14
10 / 100
 1500 ms 128388 KB 
#include <bits/stdc++.h>
using namespace std;

#define ar array
#define fi first
#define se second
#define sz(x) (int)x.size()
#define rep(i, b, e) for (int i = (b); i <= (e); i++)
#define rrep(i, b, e) for (int i = (b); i >= (e); i--)

typedef long long ll;
typedef pair<ll, ll> ii;

template <class T>
bool minimize(T &a, const T &b) {
    if(a > b) {a = b; return 1;}
    return 0;
}
template <class T>
bool maximize(T &a, const T &b) {
    if(a < b) {a = b; return 1;}
    return 0;
}

const int N = 5e3 + 7, M = 1e5 + 7;

int n, q, s[M], e[M];

void read() {
    cin >> n >> q;
    rep(i, 1, n) cin >> s[i] >> e[i];
}

int d[N][N];
vector<int> adj[N];
void sub3() {
    rep(i, 1, n) rep(j, 1, n) {
        if (s[j] <= e[i] && e[i] <= e[j]) {
            adj[i].push_back(j);
        }
    }

    memset(d, -1, sizeof d);
    rep(i, 1, n) {
        queue<int> q;
        q.push(i); d[i][i] = 0;
        while (sz(q)) {
            int u = q.front(); q.pop();
            for (int v: adj[u]) if (d[i][v] == -1) {
                d[i][v] = d[i][u] + 1;
                q.push(v);
            }
        }
    }

    while (q--) {
        int l, r;
        cin >> l >> r;
        (d[l][r] == -1 ? cout << "impossible\n" : cout << d[l][r] << '\n');
    }
}

int mn[M];
map<ii, int> pos;

int jump(int cur, int st, int des) {
    int l = st, r = des, ans = -1;
    while (l <= r) {
        int mid = l + r >> 1;
        if (mn[mid] > cur) r = mid - 1;
        else l = mid + 1, ans = mid;
    }
    return ans;
}

void sub4() {
    vector<ii> vec;
    rep(i, 1, n) vec.push_back({e[i], i});
    sort(vec.begin(), vec.end(), [&](ii x, ii y){
         return (x.fi == y.fi ? s[x.se] < s[y.se] : x.fi < y.fi);
    });
    rep(i, 0, n - 1) pos[{vec[i].fi, vec[i].se}] = i;

    for (int u, v; q; q--) {
        cin >> u >> v;

        int l = pos[{e[u], u}], r = pos[{e[v], v}], ans = 0, ok = 1;
        int cur = e[u];

        mn[r] = s[vec[r].se];
        rrep(i, r - 1, l) mn[i] = min(mn[i + 1], s[vec[i].se]);


        while (cur <= s[v]) {
            int nxt = jump(cur, l + 1, r);
            if (l != r && s[v] <= cur && cur <= e[v]) {
                l = r;
                ans++;
                break;
            }
            if (nxt == -1) {
                ok = 0;
                break;
            }
            ans++; cur = vec[nxt].fi; l = nxt;
        }
        if (l != r) ans++;
        if (l > r|| !ok) cout << "impossible\n";
        else cout << ans << '\n';
    }
}

void solve() {
    if (q <= 100) sub4();
    else if (n <= 5000) sub3();
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    if (fopen("test.inp", "r")) {
        freopen("test.inp", "r", stdin);
        freopen("test.out", "w", stdout);
    }
    read();
    solve();
}


/**
+ check mod (gõ đúng số), limit, kiểu dữ liệu
+ check format output
+mấy bài multitest:
    quên reset biến, mảng, (nên dùng fill, memset, v.v)
    quên xuống dòng
    precompute đầu bài
+nhập hết dữ liệu trước khi return
+xóa debug
**/

Compilation message

events.cpp: In function 'int jump(int, int, int)':
events.cpp:69:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   69 |         int mid = l + r >> 1;
      |                   ~~^~~
events.cpp: In function 'int main()':
events.cpp:121:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         freopen("test.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:122:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  122 |         freopen("test.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Incorrect 20 ms 3176 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 2 ms 468 KB Output is correct
4 Correct 1 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 468 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 2 ms 468 KB Output is correct
4 Correct 1 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 468 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 2 ms 468 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 1 ms 468 KB Output is correct
15 Correct 1 ms 468 KB Output is correct
16 Correct 1 ms 468 KB Output is correct
17 Correct 1 ms 468 KB Output is correct
18 Correct 1 ms 468 KB Output is correct
19 Execution timed out 1587 ms 128388 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 2 ms 468 KB Output is correct
4 Correct 1 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 468 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 2 ms 468 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 1 ms 468 KB Output is correct
15 Correct 1 ms 468 KB Output is correct
16 Correct 1 ms 468 KB Output is correct
17 Correct 1 ms 468 KB Output is correct
18 Correct 1 ms 468 KB Output is correct
19 Correct 232 ms 10976 KB Output is correct
20 Correct 76 ms 10596 KB Output is correct
21 Correct 47 ms 11304 KB Output is correct
22 Incorrect 65 ms 11284 KB Output isn't correct
23 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Incorrect 19 ms 3040 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Incorrect 20 ms 3176 KB Output isn't correct
3 Halted 0 ms 0 KB -