oj.uz

Submission #653636

# Submission time Handle Problem Language Result Execution time Memory
653636 2022-10-27T13:19:37 Z pauloamed Dango Maker (JOI18_dango_maker) C++14
33 / 100
 236 ms 262144 KB 
#include<bits/stdc++.h>
using namespace std;

// Edge structure: handles node pointed to, capacity
// and the index in v[to] to its reverse edge
struct Edge{
  int to, rev;
  int cap; //
  bool is_rev;
  Edge(int t, int c, int r, bool irev):to{t},rev{r},cap{c},is_rev{irev}
  {}
};
 
 
struct Flow{
  int n, s, t; // n: # nodes, s: source, t: sink
  vector<vector<Edge>> v; // extended adj list
  vector<int> lvl; // indicates the lvl for each node. used for the lvl graph
 
  // assures that each edge is completely visited only once. keeps sort of backup
  // of the index of the last visited edge
  // there is no need to revisit an edge, hence, these can be skipped
  vector<int> lastPos;
 
  // constructor
  Flow(int N, int src, int snk){
    this->n = N;
    this->s = src;
    this->t = snk;
    v = vector<vector<Edge>>(n, vector<Edge>());
  }
 
  // adding edges: endpoints and capacities
  // in case of bidirecitonal edges, use this function twice, one for each direction
  // using the full capacity on both
  void addEdge(int a, int b, int c){
    v[a].push_back({b,c,(int)v[b].size(),false});
    v[b].push_back({a,0,((int)v[a].size()) - 1,true});
  }
 
  // "builds" the lvl graph. simple bfs indicating the lvl for each node
  void getLvls(){
    queue<int> q; q.push(s);
    lvl.assign(n,-1); lvl[s] = 0;
    while(q.size()){
      int x = q.front(); q.pop();
      for(auto e : v[x]){
        if(lvl[e.to] == -1 && e.cap){
          // lvl graph only reaches new nodes and possible edges (cap > 0)
          q.push(e.to);
          lvl[e.to] = lvl[x] + 1;
        }
      }
    }
  }
 
  // finds an augmenting path and updates edges
  int dfs(int i, int curr = INT_MAX){
    if(i == t){
      return curr; // reached sink, returning collected flow
    }else{
      for(; lastPos[i] < v[i].size(); ++lastPos[i]){
        auto &e = v[i][lastPos[i]];
        if(e.cap && lvl[i] + 1 == lvl[e.to]){
          // possible edges (cap > 0) and lvl-graph structure (consecutive lvls traversal)
 
          int maybe_flow = dfs(e.to, min(curr, e.cap));
          if(maybe_flow == 0) continue;
 
          e.cap -= maybe_flow; // updating edge
          v[e.to][e.rev].cap += maybe_flow; // and its reverse
          return maybe_flow;
        }
      }
    }
    return 0;
  }
 
  // main funct
  int run(){
    int flow = 0; // initial flow
    while(true){
      getLvls(); // builds lvl graph
      // if the sink cant be reached, the max flow has been found
      if(lvl[t]==-1) break;
      // get a blocking flow for the current lvl graph
      int blocking = -1;
      lastPos.assign(n,0);
      while((blocking = dfs(s))) flow += blocking;
    }
    return flow;
  }
 
  vector<pair<int,int>> get_cut(){
    vector<pair<int,int>> cut;
    for(int i = 0; i < n; ++i){
      for(int j = 0; j < v[i].size(); ++j){
        auto &e = v[i][j];
        if(!e.is_rev && lvl[i] != -1 && lvl[e.to] == -1){
          cut.push_back({i, e.to});
        }
      }
    }
    return cut;
  }
};

const int SRC = 0;
const int SINK = 1;
const int OFFSET = 2;


const int MAXN = 3001;
string s[MAXN];

int idv[MAXN][MAXN];
int idh[MAXN][MAXN];

int main(){
  memset(idv, -1, sizeof idv);
  memset(idh, -1, sizeof idh);

  cin.tie(NULL)->sync_with_stdio(false);
  int n, m; cin >> n >> m;
  for(int i = 0; i < n; ++i){
    cin >> s[i];
    s[i].shrink_to_fit();
  }

  int curr_idv = 0;
  int curr_idh = 0;

  for(int i = 0; i < n; ++i){
    for(int j = 0; j < m; ++j){
      // ver
      if(i + 2 < n){
        if((s[i][j] == 'R') && (s[i+1][j] == 'G') && (s[i+2][j] == 'W')){
          idv[i][j] = curr_idv;
          idv[i+1][j] = curr_idv;
          idv[i+2][j] = curr_idv;
          curr_idv++;
        }
      }

      if(j + 2 < m){
        if((s[i][j] == 'R') && (s[i][j+1] == 'G') && (s[i][j+2] == 'W')){
          idh[i][j] = curr_idh;
          idh[i][j+1] = curr_idh;
          idh[i][j+2] = curr_idh;
          curr_idh++;
        }
      }
    }
  }

  for(int i = 0; i < n; ++i) s[i].clear();
  // ESQ: VERTICAIS
  // DIR: HORIZONTAIS

  Flow f(2 + curr_idh + curr_idv, SRC, SINK);
  for(int i = 0; i < curr_idv; ++i){
    f.addEdge(SRC, i + OFFSET, 1);
  }
  for(int i = 0; i < curr_idh; ++i){
    f.addEdge(i + curr_idv + OFFSET, SINK, 1);
  }

  for(int i = 0; i < n; ++i){
    for(int j = 0; j < m; ++j){
      if(idh[i][j] != -1 && idv[i][j] != -1){
        // cout << i << " " << j << " " << idv[i][j][0] << " " << idh[i][j][0] << endl;
        f.addEdge(idv[i][j] + OFFSET, curr_idv + idh[i][j] + OFFSET, 1);
      }
    }
  }

  int x = f.run();
  // cout << x << " " << curr_idh << " " << curr_idv<< endl;
  cout << curr_idh + curr_idv - x << "\n";
}

Compilation message

dango_maker.cpp: In member function 'int Flow::dfs(int, int)':
dango_maker.cpp:62:24: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} and 'std::vector<Edge>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |       for(; lastPos[i] < v[i].size(); ++lastPos[i]){
dango_maker.cpp: In member function 'std::vector<std::pair<int, int> > Flow::get_cut()':
dango_maker.cpp:97:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Edge>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |       for(int j = 0; j < v[i].size(); ++j){
      |                      ~~^~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 70812 KB Output is correct
2 Correct 27 ms 70868 KB Output is correct
3 Correct 26 ms 70860 KB Output is correct
4 Correct 29 ms 70868 KB Output is correct
5 Correct 27 ms 70856 KB Output is correct
6 Correct 31 ms 70832 KB Output is correct
7 Correct 27 ms 70884 KB Output is correct
8 Correct 28 ms 70812 KB Output is correct
9 Correct 27 ms 70864 KB Output is correct
10 Correct 27 ms 70904 KB Output is correct
11 Correct 28 ms 70880 KB Output is correct
12 Correct 27 ms 70868 KB Output is correct
13 Correct 27 ms 70836 KB Output is correct
14 Correct 27 ms 70868 KB Output is correct
15 Correct 31 ms 70884 KB Output is correct
16 Correct 27 ms 70888 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 70812 KB Output is correct
2 Correct 27 ms 70868 KB Output is correct
3 Correct 26 ms 70860 KB Output is correct
4 Correct 29 ms 70868 KB Output is correct
5 Correct 27 ms 70856 KB Output is correct
6 Correct 31 ms 70832 KB Output is correct
7 Correct 27 ms 70884 KB Output is correct
8 Correct 28 ms 70812 KB Output is correct
9 Correct 27 ms 70864 KB Output is correct
10 Correct 27 ms 70904 KB Output is correct
11 Correct 28 ms 70880 KB Output is correct
12 Correct 27 ms 70868 KB Output is correct
13 Correct 27 ms 70836 KB Output is correct
14 Correct 27 ms 70868 KB Output is correct
15 Correct 31 ms 70884 KB Output is correct
16 Correct 27 ms 70888 KB Output is correct
17 Correct 35 ms 70792 KB Output is correct
18 Correct 28 ms 70868 KB Output is correct
19 Correct 27 ms 70904 KB Output is correct
20 Correct 27 ms 70868 KB Output is correct
21 Correct 27 ms 70840 KB Output is correct
22 Correct 27 ms 70856 KB Output is correct
23 Correct 27 ms 70800 KB Output is correct
24 Correct 27 ms 70840 KB Output is correct
25 Correct 31 ms 70820 KB Output is correct
26 Correct 27 ms 70832 KB Output is correct
27 Correct 27 ms 70816 KB Output is correct
28 Correct 27 ms 70796 KB Output is correct
29 Correct 32 ms 70888 KB Output is correct
30 Correct 28 ms 70868 KB Output is correct
31 Correct 27 ms 70804 KB Output is correct
32 Correct 27 ms 70896 KB Output is correct
33 Correct 31 ms 70792 KB Output is correct
34 Correct 29 ms 70844 KB Output is correct
35 Correct 28 ms 70860 KB Output is correct
36 Correct 27 ms 70868 KB Output is correct
37 Correct 28 ms 70912 KB Output is correct
38 Correct 28 ms 70896 KB Output is correct
39 Correct 27 ms 70892 KB Output is correct
40 Correct 28 ms 70852 KB Output is correct
41 Correct 28 ms 70868 KB Output is correct
42 Correct 27 ms 70832 KB Output is correct
43 Correct 27 ms 70784 KB Output is correct
44 Correct 28 ms 70848 KB Output is correct
45 Correct 27 ms 70868 KB Output is correct
46 Correct 27 ms 70856 KB Output is correct
47 Correct 29 ms 70924 KB Output is correct
48 Correct 27 ms 70868 KB Output is correct
49 Correct 27 ms 70920 KB Output is correct
50 Correct 28 ms 70868 KB Output is correct
51 Correct 27 ms 70868 KB Output is correct
52 Correct 27 ms 70856 KB Output is correct
53 Correct 27 ms 70844 KB Output is correct

Subtask #3
0 / 67.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 70812 KB Output is correct
2 Correct 27 ms 70868 KB Output is correct
3 Correct 26 ms 70860 KB Output is correct
4 Correct 29 ms 70868 KB Output is correct
5 Correct 27 ms 70856 KB Output is correct
6 Correct 31 ms 70832 KB Output is correct
7 Correct 27 ms 70884 KB Output is correct
8 Correct 28 ms 70812 KB Output is correct
9 Correct 27 ms 70864 KB Output is correct
10 Correct 27 ms 70904 KB Output is correct
11 Correct 28 ms 70880 KB Output is correct
12 Correct 27 ms 70868 KB Output is correct
13 Correct 27 ms 70836 KB Output is correct
14 Correct 27 ms 70868 KB Output is correct
15 Correct 31 ms 70884 KB Output is correct
16 Correct 27 ms 70888 KB Output is correct
17 Correct 35 ms 70792 KB Output is correct
18 Correct 28 ms 70868 KB Output is correct
19 Correct 27 ms 70904 KB Output is correct
20 Correct 27 ms 70868 KB Output is correct
21 Correct 27 ms 70840 KB Output is correct
22 Correct 27 ms 70856 KB Output is correct
23 Correct 27 ms 70800 KB Output is correct
24 Correct 27 ms 70840 KB Output is correct
25 Correct 31 ms 70820 KB Output is correct
26 Correct 27 ms 70832 KB Output is correct
27 Correct 27 ms 70816 KB Output is correct
28 Correct 27 ms 70796 KB Output is correct
29 Correct 32 ms 70888 KB Output is correct
30 Correct 28 ms 70868 KB Output is correct
31 Correct 27 ms 70804 KB Output is correct
32 Correct 27 ms 70896 KB Output is correct
33 Correct 31 ms 70792 KB Output is correct
34 Correct 29 ms 70844 KB Output is correct
35 Correct 28 ms 70860 KB Output is correct
36 Correct 27 ms 70868 KB Output is correct
37 Correct 28 ms 70912 KB Output is correct
38 Correct 28 ms 70896 KB Output is correct
39 Correct 27 ms 70892 KB Output is correct
40 Correct 28 ms 70852 KB Output is correct
41 Correct 28 ms 70868 KB Output is correct
42 Correct 27 ms 70832 KB Output is correct
43 Correct 27 ms 70784 KB Output is correct
44 Correct 28 ms 70848 KB Output is correct
45 Correct 27 ms 70868 KB Output is correct
46 Correct 27 ms 70856 KB Output is correct
47 Correct 29 ms 70924 KB Output is correct
48 Correct 27 ms 70868 KB Output is correct
49 Correct 27 ms 70920 KB Output is correct
50 Correct 28 ms 70868 KB Output is correct
51 Correct 27 ms 70868 KB Output is correct
52 Correct 27 ms 70856 KB Output is correct
53 Correct 27 ms 70844 KB Output is correct
54 Correct 27 ms 70888 KB Output is correct
55 Correct 28 ms 70908 KB Output is correct
56 Correct 28 ms 71160 KB Output is correct
57 Correct 30 ms 71196 KB Output is correct
58 Correct 51 ms 79416 KB Output is correct
59 Correct 235 ms 141528 KB Output is correct
60 Correct 236 ms 141612 KB Output is correct
61 Correct 236 ms 141476 KB Output is correct
62 Correct 27 ms 70804 KB Output is correct
63 Correct 233 ms 139396 KB Output is correct
64 Runtime error 175 ms 262144 KB Execution killed with signal 9
65 Halted 0 ms 0 KB -