1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
| #include <bits/stdc++.h>
using namespace std;
int nx[] = {-1, 0, 1, 0};
int ny[] = {0, 1, 0, -1};
int N, M;
int a[105][105];
int c[105][105];
int cnt1, cnt2;
vector<int> G[20005];
bool vis[20005];
int m[20005];
bool tag[20005];
vector<pair<int, int> > Out;
bool find(int u) {
if (vis[u]) return 0;
vis[u] = 1;
for (vector<int>::iterator it = G[u].begin(); it != G[u].end(); it++) {
int v = *it;
if (m[v] == 0 || find(m[v])) {
m[u] = v, m[v] = u;
return 1;
}
}
return 0;
}
bool dfs(int u) {
if (vis[u]) return 0;
vis[u] = 1;
if (m[u] == 0) return 1;
for (vector<int>::iterator it = G[m[u]].begin(); it != G[m[u]].end(); it++) {
int v = *it;
if (dfs(v)) return 1;
}
return 0;
}
int main() {
cin >> N >> M;
for (int i = 1; i <= N; ++i) {
for (int j = 1; j <= M; ++j) {
char ch;
cin >> ch;
if (ch == '#') continue;
if ((i + j) & 1) c[i][j] = ++cnt1;
else c[i][j] = ++cnt2 + 10000;
}
}
for (int i = 1; i <= N; ++i) {
for (int j = 1; j <= M; ++j) {
if (c[i][j] == 0) continue;
for (int k = 0; k < 4; ++k) {
int ti = i + nx[k], tj = j + ny[k];
if (ti >= 1 && ti <= N && tj >= 1 && tj <= M) {
if (c[ti][tj]) G[c[i][j]].push_back(c[ti][tj]);
}
}
}
}
for (int i = 1; i <= cnt1; ++i) {
memset(vis, 0, sizeof(vis));
find(i);
}
for (int i = 1; i <= N; ++i) {
for (int j = 1; j <= M; ++j) {
if (c[i][j] == 0) continue;
memset(vis, 0, sizeof(vis));
if (dfs(c[i][j])) {
Out.push_back(make_pair(i, j));
}
}
}
printf("%d\n", Out.size());
for (int i = 0; i < (int)Out.size(); ++i)
printf("%d %d\n", Out[i].first, Out[i].second);
return 0;
}
|