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답안 #583368

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
583368 2022-06-25T09:50:52 Z 600Mihnea One-Way Streets (CEOI17_oneway) C++17
100 / 100
 234 ms 57396 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], gp[N], gn[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;
}

void dfstot(int a, int p = 0) {
  for (auto &b : g[a]) {
    if (b != p) {
      dfstot(b, a);
    }
  }
  gp[p] = max(gp[p], gp[a] - 1);
  gn[p] = max(gn[p], gn[a] - 1);
}

int dir[N];

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

  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);
  }

  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;
  }
  vector<int> rts;
  for (int i = 1; i <= currentColor; i++) {
    if (vis[i] == 0) {
      dep[i] = 0;
      rts.push_back(i);
      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))]);
    }
  }

  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);
    gn[a] = max(gn[a], dep[a] - dep[c]);
    gp[b] = max(gp[b], dep[b] - dep[c]);
  }

  for (auto &i : rts) {
    dfstot(i);
  }
  for (int i = 1; i <= currentColor; i++) {
    assert((gp[i] == 0) || (gn[i] == 0));
    if (gp[i]) {
      dir[i] = +1;
    }
    if (gn[i]) {
      dir[i] = -1;
    }
    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

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 3 ms 5204 KB Output is correct
4 Correct 4 ms 5460 KB Output is correct
5 Correct 3 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

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 3 ms 5204 KB Output is correct
4 Correct 4 ms 5460 KB Output is correct
5 Correct 3 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 33 ms 10016 KB Output is correct
12 Correct 37 ms 11516 KB Output is correct
13 Correct 56 ms 14192 KB Output is correct
14 Correct 69 ms 22624 KB Output is correct
15 Correct 87 ms 26136 KB Output is correct
16 Correct 172 ms 49428 KB Output is correct
17 Correct 161 ms 52588 KB Output is correct
18 Correct 154 ms 49996 KB Output is correct
19 Correct 177 ms 54380 KB Output is correct
20 Correct 41 ms 10884 KB Output is correct
21 Correct 42 ms 11292 KB Output is correct

Subtask #3
40.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 5076 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 3 ms 5204 KB Output is correct
4 Correct 4 ms 5460 KB Output is correct
5 Correct 3 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 33 ms 10016 KB Output is correct
12 Correct 37 ms 11516 KB Output is correct
13 Correct 56 ms 14192 KB Output is correct
14 Correct 69 ms 22624 KB Output is correct
15 Correct 87 ms 26136 KB Output is correct
16 Correct 172 ms 49428 KB Output is correct
17 Correct 161 ms 52588 KB Output is correct
18 Correct 154 ms 49996 KB Output is correct
19 Correct 177 ms 54380 KB Output is correct
20 Correct 41 ms 10884 KB Output is correct
21 Correct 42 ms 11292 KB Output is correct
22 Correct 205 ms 52576 KB Output is correct
23 Correct 228 ms 50104 KB Output is correct
24 Correct 234 ms 50096 KB Output is correct
25 Correct 213 ms 57396 KB Output is correct
26 Correct 206 ms 51916 KB Output is correct
27 Correct 214 ms 50152 KB Output is correct
28 Correct 28 ms 7376 KB Output is correct
29 Correct 58 ms 10336 KB Output is correct
30 Correct 59 ms 10832 KB Output is correct
31 Correct 61 ms 10944 KB Output is correct
32 Correct 96 ms 25280 KB Output is correct