Cod sursa(job #2673275)

Utilizator FunnyStockyMihnea Andreescu FunnyStocky Data 16 noiembrie 2020 14:02:32
Problema Felinare Scor 40
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 3 kb
#include <iostream>
#include <vector>
#include <cstdio>
#include <queue>

using namespace std;

int sol[9000];

struct flow {
  struct E {
    int to;
    int cap;
  };
  const int INF = (int) 1e9;
  int n;
  int nn;
  vector<vector<int>> g;
  vector<E> edges;
  vector<int> level;
  vector<int> pos;
  vector<int> go;
  void init(int nn) {
    n = nn;
    g.clear();
    edges.clear();
    level.clear();
    pos.clear();
    level.resize(n + 1);
    g.resize(n + 1);
    pos.resize(n + 1);
  }
  void add(int a, int b, int c) {
    g[a].push_back((int) edges.size());
    g[b].push_back((int) edges.size() + 1);
    edges.push_back({b, c});
    edges.push_back({a, 0});
    go.push_back(0);
    go.push_back(0);
  }
  vector<int> path;
  void run(int a) {
    path.push_back(a);
    if (a == n) {
      int x = path[1] - 1;
      int y = path[2] - 1 - nn;
      if (sol[x] & 1) {
        sol[x]--;
      }
      if (sol[y] & 2) {
        sol[y] -= 2;
      }
      path.pop_back();
      return;
    }
    for (auto &i : g[a]) {
      if (go[i]) {
        int b = edges[i].to;
        run(b);
        go[i]--;
      }
    }
    path.pop_back();
  }
  int dfs(int a, int cap) {
    if (a == n || cap == 0) {
      return cap;
    }
    while (pos[a] < (int) g[a].size()) {
      int i = g[a][pos[a]++];
      int b = edges[i].to;
      int c = edges[i].cap;
      if (c == 0 || level[b] != level[a] + 1) {
        continue;
      }
      int x = dfs(b, min(cap, c));
      if (x == 0) {
        continue;
      }
      if (i & 1) {
        go[i ^ 1] -= x;
      } else {
        go[i] += x;
      }
      edges[i].cap -= x;
      edges[i ^ 1].cap += x;
      return x;
    }
    return 0;
  }
  int get() {
    int ret = 0;
    while (1) {
      level[1] = pos[1] = 0;
      for (int i = 2; i <= n; i++) {
        level[i] = -1;
        pos[i] = 0;
      }
      queue<int> q;
      q.push(1);
      while (!q.empty()) {
        int a = q.front();
        q.pop();
        for (auto &i : g[a]) {
          int b = edges[i].to;
          int c = edges[i].cap;
          if (c > 0 && level[b] == -1) {
            level[b] = 1 + level[a];
            q.push(b);
          }
        }
      }
      if (level[n] == -1) {
        break;
      }
      while (1) {
        int x = dfs(1, INF);
        if (x == 0) {
          break;
        }
        ret += x;
      }
    }
    return ret;
  }
};

signed main() {
  freopen ("felinare.in", "r", stdin);
  freopen ("felinare.out", "w", stdout);

  int n, m;
  flow f;
  scanf("%d %d", &n, &m);
  f.init(2 * n + 2);
  for (int i = 1; i <= n; i++) {
    sol[i] = 3;
    f.add(1, 1 + i, 1);
    f.add(1 + n + i, 2 * n + 2, 1);
  }
  for (int i = 1; i <= m; i++) {
    int x, y;
    scanf("%d %d", &x, &y);
    f.add(1 + x, 1 + n + y, (int) 1e9);
  }
  printf("%d\n", 2 * n - f.get());
  f.nn = n;
  f.run(1);
  for (int i = 1; i <= n; i++) {
    printf("%d\n", sol[i]);
  }
}