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Submission #659840

# Submission time Handle Problem Language Result Execution time Memory
659840 2022-11-19T12:02:58 Z 600Mihnea Event Hopping (BOI22_events) C++17
10 / 100
 1500 ms 1492 KB 
bool home = 0;
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
const int N = (int) 1e5 + 7;
int n;
int q;

struct T {
  int l;
  int r;
  int init;
};

bool operator < (T a, T b) {
  if (a.r != b.r) {
    return a.r < b.r;
  } else {
    return a.l < b.l;
  }
}

T v[N];
int dp[N];
int nxt[N];
int ant[N];
int inv[N];

int cnt_rs_under(int limit) {
  int low = 1, high = n, cnt = 0;
  while (low <= high) {
    int mid = (low + high) / 2;
    if (v[mid].r <= limit) {
      cnt = mid;
      low = mid + 1;
    } else {
      high = mid - 1;
    }
  }
  return cnt;
}

int main() {
  if (!home) {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  } else {
    freopen("input.txt", "r", stdin);
  }

  cin >> n >> q;
  for (int i = 1; i <= n; i++) {
    cin >> v[i].l >> v[i].r;
    v[i].init = i;
  }
  sort(v + 1, v + n + 1);
  for (int i = 1; i <= n; i++) {
    int x = cnt_rs_under(v[i].l - 1) + 1;
    int y = cnt_rs_under(v[i].r);
    for (int j = 1; j <= n; j++) {
      assert((v[i].l <= v[j].r && v[j].r <= v[i].r) == (x <= j && j <= y));
    }
  }
  for (int i = 1; i <= n; i++) {
    inv[v[i].init] = i;
  }
  for (int i = 1; i <= n; i++) {
    nxt[i] = -1;
    for (int j = 1; j <= n; j++) {
      if (v[j].l <= v[i].r) {
        if (nxt[i] == -1) {
          nxt[i] = j;
        } else {
          if (v[j].r > v[nxt[i]].r) {
            nxt[i] = j;
          }
        }
      }
    }
    if (nxt[i] != -1 && v[i].r >= v[nxt[i]].r) {
      nxt[i] = -1;
    }
  }
  for (int i = 1; i <= n; i++) {
    ant[i] = -1;
    for (int j = 1; j <= n; j++) {
      if (v[i].l <= v[j].r && v[j].r <= v[i].l) {
        if (ant[i] == -1) {
          ant[i] = j;
        }
      } else {
        if (v[j].l < v[ant[i]].l) {
          ant[i] = j;
        }
      }
    }
  }
  for (int iq = 1; iq <= q; iq++) {
    int ff, ss;
    cin >> ff >> ss;
    ff = inv[ff];
    ss = inv[ss];
    for (int i = 1; i <= n; i++) {
      dp[i] = -1;
    }
    int co = 0;
    while (nxt[ff] != -1 && v[nxt[ff]].r <= v[ss].l) {
      ff = nxt[ff];
      co++;
    }
    while (ant[ss] != -1 && v[ant[ss]].l >= v[ss].r) {
      ss = ant[ss];
      co++;
    }
    queue<int> q;
    q.push(ff);
    dp[ff] = 0;
    while (!q.empty()) {
      int a = q.front();
      q.pop();
      for (int b = 1; b <= n; b++) {
        if (v[b].l <= v[a].r && v[a].r <= v[b].r && dp[b] == -1) {
          dp[b] = 1 + dp[a];
          q.push(b);
        }
      }
    }
    if (dp[ss] == -1) {
      cout << "impossible\n";
      continue;
    }
    cout << co + dp[ss] << "\n";
  }

  return 0;
}
/**

**/

Compilation message

events.cpp: In function 'int main()':
events.cpp:49:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Execution timed out 1592 ms 1440 KB Time limit exceeded
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 384 KB Output is correct
3 Correct 6 ms 352 KB Output is correct
4 Correct 38 ms 340 KB Output is correct
5 Correct 137 ms 348 KB Output is correct
6 Correct 90 ms 340 KB Output is correct
7 Correct 149 ms 340 KB Output is correct
8 Correct 128 ms 356 KB Output is correct
9 Correct 264 ms 356 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 384 KB Output is correct
3 Correct 6 ms 352 KB Output is correct
4 Correct 38 ms 340 KB Output is correct
5 Correct 137 ms 348 KB Output is correct
6 Correct 90 ms 340 KB Output is correct
7 Correct 149 ms 340 KB Output is correct
8 Correct 128 ms 356 KB Output is correct
9 Correct 264 ms 356 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 6 ms 340 KB Output is correct
13 Correct 38 ms 340 KB Output is correct
14 Correct 137 ms 348 KB Output is correct
15 Correct 90 ms 340 KB Output is correct
16 Correct 151 ms 356 KB Output is correct
17 Correct 128 ms 356 KB Output is correct
18 Correct 263 ms 372 KB Output is correct
19 Execution timed out 1589 ms 372 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 1 ms 384 KB Output is correct
3 Correct 6 ms 352 KB Output is correct
4 Correct 38 ms 340 KB Output is correct
5 Correct 137 ms 348 KB Output is correct
6 Correct 90 ms 340 KB Output is correct
7 Correct 149 ms 340 KB Output is correct
8 Correct 128 ms 356 KB Output is correct
9 Correct 264 ms 356 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 6 ms 360 KB Output is correct
13 Correct 39 ms 340 KB Output is correct
14 Correct 138 ms 460 KB Output is correct
15 Correct 90 ms 340 KB Output is correct
16 Correct 149 ms 356 KB Output is correct
17 Correct 129 ms 368 KB Output is correct
18 Correct 263 ms 368 KB Output is correct
19 Execution timed out 1571 ms 1492 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1593 ms 1492 KB Time limit exceeded
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 Execution timed out 1592 ms 1440 KB Time limit exceeded
3 Halted 0 ms 0 KB -