oj.uz

Submission #697958

# Submission time Handle Problem Language Result Execution time Memory
697958 2023-02-11T15:15:55 Z Neos Event Hopping (BOI22_events) C++14
25 / 100
 1500 ms 128652 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]);

        if (u == v) {
            cout << "0\n";
            continue;
        }
        if (s[v] <= cur && cur <= e[v]) {
            cout << 1 << '\n';
            continue;
        }
        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:128:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |         freopen("test.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:129:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |         freopen("test.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Incorrect 19 ms 1208 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 0 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 3 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 0 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 3 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 Execution timed out 1555 ms 128652 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 3 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 Correct 229 ms 9344 KB Output is correct
20 Correct 72 ms 9412 KB Output is correct
21 Correct 60 ms 9408 KB Output is correct
22 Correct 65 ms 9400 KB Output is correct
23 Correct 56 ms 11328 KB Output is correct
24 Correct 70 ms 11328 KB Output is correct
25 Correct 47 ms 10396 KB Output is correct

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Incorrect 19 ms 1108 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Incorrect 19 ms 1208 KB Output isn't correct
3 Halted 0 ms 0 KB -