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Submission #583364

# Submission time Handle Problem Language Result Execution time Memory
583364 2022-06-25T09:42:54 Z 600Mihnea One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 54800 KB 
#include <bits/stdc++.h>

using namespace std;

const int N = (int) 1e5 + 7;
const int K = 20;
vector<int> g[N], g2[N];
int n, m, q, sumEdge[N], dep[N], mindep[N], xx[N], yy[N], ff[N], ss[N], top, lg2[2 * N], par[N], sol[N];
pair<int, int> rmq[K][2 * N];
bool isBridge[N];
bool vis[N];
int color[N], currentColor;
map<pair<int, int>, int> coresp;

void dfs_build_bridges(int a, int parrent_edge_id = 0) {
  mindep[a] = dep[a];
  vector<int> downEdges;
  for (auto &i : g[a]) {
    int b = sumEdge[i] - a;
    if (dep[b] == -1) {
      dep[b] = 1 + dep[a];
      dfs_build_bridges(b, i);
      mindep[a] = min(mindep[a], mindep[b]);
      downEdges.push_back(i);
      continue;
    }
    if (i == parrent_edge_id) {
      continue;
    }
    mindep[a] = min(mindep[a], dep[b]);
  }
  for (auto &i : downEdges) {
    int b = sumEdge[i] - a;
    if (dep[a] < mindep[b]) {
      isBridge[i] = 1;
    }
  }
}

void dfsColor(int a) {
  color[a] = currentColor;
  for (auto &i : g[a]) {
    int b = sumEdge[i] - a;
    if (isBridge[i]) {
      if (color[b]) {
        coresp[{color[xx[i]], color[yy[i]]}] = i;
        g2[color[a]].push_back(color[b]);
        g2[color[b]].push_back(color[a]);
      }
      continue;
    }
    if (color[b] == 0) {
      dfsColor(b);
    }
  }
}

void dfs(int a) {
  vis[a] = 1;
  rmq[0][++top] = {dep[a], a};
  ff[a] = ss[a] = top;
  for (auto &b : g[a]) {
    if (vis[b] == 0) {
      par[b] = a;
      dep[b] = 1 + dep[a];
      dfs(b);
      rmq[0][++top] = {dep[a], a};
      ss[a] = top;
    }
  }
}

int getLca(int a, int b) {
  if (ff[a] > ss[b]) {
    swap(a, b);
  }
  assert(ff[a] <= ss[b]);
  a = ff[a];
  b = ss[b];
  int k = lg2[b - a + 1];
  return min(rmq[k][a], rmq[k][b - (1 << k) + 1]).second;
}

int dir[N];

signed main() {
  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

///  freopen ("input.txt", "r", stdin);
///  freopen ("output.txt", "w", stdout);
///

  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    dep[i] = -1;
  }
  for (int i = 1; i <= m; i++) {
    int a, b;
    cin >> a >> b;
    xx[i] = a;
    yy[i] = b;
    sumEdge[i] = a + b;
    g[a].push_back(i);
    g[b].push_back(i);
  }
  /// build the Tree

  for (int i = 1; i <= n; i++) {
    if (dep[i] == -1) {
      dep[i] = 0;
      dfs_build_bridges(i);
    }
  }


  for (int i = 1; i <= n; i++) {
    if (color[i] == 0) {
      currentColor++;
      dfsColor(i);
    }
  }

  for (int i = 1; i <= currentColor; i++) {
    g[i] = g2[i];
  }

  for (int i = 1; i <= currentColor; i++) {
    vis[i] = 0;
    dep[i] = 0;
  }
  for (int i = 1; i <= currentColor; i++) {
    if (vis[i] == 0) {
      dep[i] = 0;
      dfs(i);
    }
  }
  for (int i = 2; i <= top; i++) {
    lg2[i] = 1 + lg2[i / 2];
  }
  for (int k = 1; (1 << k) <= top; k++) {
    for (int i = 1; i + (1 << k) - 1 <= top; i++) {
      rmq[k][i] = min(rmq[k - 1][i], rmq[k - 1][i + (1 << (k - 1))]);
    }
  }
 /* exit(0);
  for (int i = 1; i <= n; i++) {
    cout << i << " : " << color[i] << "\n";
  }

  cout << "----------------\n";

  for (int i = 1; i <= currentColor; i++) {
    for (auto &j : g[i]) {
      cout << "Edge = " << i << " " << j << "\n";
    }
  }

  return 0;

  for (int i = 1; i <= m; i++) {
    if (isBridge[i]) {
      cout << "bridge : " << xx[i] << " " << yy[i] << "\n";
    }
  }*/




  cin >> q;

  for (int i = 1; i <= q; i++) {
    int a, b;
    cin >> a >> b;
    a = color[a];
    b = color[b];
    int c = getLca(a, b);
    //cout << a << " " << b << " -> " << c << "\n";
    while (a != c) {
      assert(a > 0);
      assert(dir[a] == -1 || dir[a] == 0);
      dir[a] = -1;
      a = par[a];
    }
    while (b != c) {
      assert(b > 0);
      assert(dir[b] == +1 || dir[b] == 0);
      dir[b] = +1;
      b = par[b];
    }
  }

  for (int i = 1; i <= currentColor; i++) {
    if (dir[i] != 0) {

      assert(coresp.count({i, par[i]}) || coresp.count({par[i], i}));
      if (coresp.count({i, par[i]})) {
        sol[coresp[{i, par[i]}]] = dir[i];
      } else {
        sol[coresp[{par[i], i}]] = -dir[i];
      }
    }
  }
  for (int i = 1; i <= m; i++) {
    if (sol[i] == 0) {
      cout << "B";
    } else {
      if (sol[i] == -1) {
        cout << "R";
      } else {
        assert(sol[i] == +1);
        cout << "L";
      }
    }
  }
  cout << "\n";
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 4 ms 5168 KB Output is correct
4 Correct 4 ms 5424 KB Output is correct
5 Correct 5 ms 5460 KB Output is correct
6 Correct 3 ms 5076 KB Output is correct
7 Correct 4 ms 5460 KB Output is correct
8 Correct 4 ms 5460 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5204 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 4 ms 5168 KB Output is correct
4 Correct 4 ms 5424 KB Output is correct
5 Correct 5 ms 5460 KB Output is correct
6 Correct 3 ms 5076 KB Output is correct
7 Correct 4 ms 5460 KB Output is correct
8 Correct 4 ms 5460 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5204 KB Output is correct
11 Correct 36 ms 11084 KB Output is correct
12 Correct 45 ms 12560 KB Output is correct
13 Correct 56 ms 15328 KB Output is correct
14 Correct 88 ms 23260 KB Output is correct
15 Correct 83 ms 26828 KB Output is correct
16 Correct 151 ms 49884 KB Output is correct
17 Correct 173 ms 52936 KB Output is correct
18 Correct 164 ms 50444 KB Output is correct
19 Correct 221 ms 54800 KB Output is correct
20 Correct 44 ms 12108 KB Output is correct
21 Correct 42 ms 12300 KB Output is correct

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 4 ms 5168 KB Output is correct
4 Correct 4 ms 5424 KB Output is correct
5 Correct 5 ms 5460 KB Output is correct
6 Correct 3 ms 5076 KB Output is correct
7 Correct 4 ms 5460 KB Output is correct
8 Correct 4 ms 5460 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5204 KB Output is correct
11 Correct 36 ms 11084 KB Output is correct
12 Correct 45 ms 12560 KB Output is correct
13 Correct 56 ms 15328 KB Output is correct
14 Correct 88 ms 23260 KB Output is correct
15 Correct 83 ms 26828 KB Output is correct
16 Correct 151 ms 49884 KB Output is correct
17 Correct 173 ms 52936 KB Output is correct
18 Correct 164 ms 50444 KB Output is correct
19 Correct 221 ms 54800 KB Output is correct
20 Correct 44 ms 12108 KB Output is correct
21 Correct 42 ms 12300 KB Output is correct
22 Execution timed out 3057 ms 52816 KB Time limit exceeded
23 Halted 0 ms 0 KB -