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Submission #659841

# Submission time Handle Problem Language Result Execution time Memory
659841 2022-11-19T12:03:21 Z 600Mihnea Event Hopping (BOI22_events) C++17
10 / 100
 1500 ms 1496 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 - 1);
    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 1579 ms 1492 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 0 ms 340 KB Output is correct
3 Correct 5 ms 340 KB Output is correct
4 Correct 41 ms 340 KB Output is correct
5 Correct 138 ms 356 KB Output is correct
6 Correct 92 ms 360 KB Output is correct
7 Correct 156 ms 356 KB Output is correct
8 Correct 130 ms 356 KB Output is correct
9 Correct 267 ms 364 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 0 ms 340 KB Output is correct
3 Correct 5 ms 340 KB Output is correct
4 Correct 41 ms 340 KB Output is correct
5 Correct 138 ms 356 KB Output is correct
6 Correct 92 ms 360 KB Output is correct
7 Correct 156 ms 356 KB Output is correct
8 Correct 130 ms 356 KB Output is correct
9 Correct 267 ms 364 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 5 ms 336 KB Output is correct
13 Correct 38 ms 340 KB Output is correct
14 Correct 133 ms 352 KB Output is correct
15 Correct 91 ms 340 KB Output is correct
16 Correct 153 ms 356 KB Output is correct
17 Correct 130 ms 356 KB Output is correct
18 Correct 266 ms 356 KB Output is correct
19 Execution timed out 1581 ms 436 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 0 ms 340 KB Output is correct
3 Correct 5 ms 340 KB Output is correct
4 Correct 41 ms 340 KB Output is correct
5 Correct 138 ms 356 KB Output is correct
6 Correct 92 ms 360 KB Output is correct
7 Correct 156 ms 356 KB Output is correct
8 Correct 130 ms 356 KB Output is correct
9 Correct 267 ms 364 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 1 ms 340 KB Output is correct
12 Correct 5 ms 340 KB Output is correct
13 Correct 37 ms 340 KB Output is correct
14 Correct 133 ms 356 KB Output is correct
15 Correct 90 ms 348 KB Output is correct
16 Correct 151 ms 360 KB Output is correct
17 Correct 128 ms 468 KB Output is correct
18 Correct 264 ms 340 KB Output is correct
19 Execution timed out 1589 ms 1496 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 1597 ms 1472 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 1579 ms 1492 KB Time limit exceeded
3 Halted 0 ms 0 KB -