This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
template<class C>constexpr int sz(const C&c){return int(c.size());}
using ll=long long;constexpr const char nl='\n',sp=' ';
template <const int MAXV> struct HopcroftKarpMaxMatch {
int mate[MAXV], lvl[MAXV + 1], q[MAXV]; vector<int> adj[MAXV], type[2]; bool color[MAXV], inCover[MAXV], vis[MAXV];
void addEdge(int v, int w) { adj[v].push_back(w); adj[w].push_back(v); }
bool bfs(int V) {
lvl[V] = -1; int front = 0, back = 0;
for (int v : type[0]) {
if (mate[v] == V) lvl[q[back++] = v] = 0;
else lvl[v] = -1;
}
while (front < back) {
int v = q[front++];
for (int w : adj[v]) if (lvl[mate[w]] == -1) {
lvl[mate[w]] = lvl[v] + 1;
if (mate[w] == V) return true;
else q[back++] = mate[w];
}
}
return lvl[V] != -1;
}
bool dfs(int V, int v) {
for (int w : adj[v]) if (lvl[mate[w]] == lvl[v] + 1 && (mate[w] == V || dfs(V, mate[w]))) { mate[mate[v] = w] = v; return true; }
lvl[v] = -1; return false;
}
void init(int V) { for (int i = 0; i < V; i++) { adj[i].clear(); color[i] = false; } }
int getMaxMatch(int V) {
int cardinality = 0;
for (int i = 0; i < 2; i++) type[i].clear();
for (int v = 0; v < V; v++) { type[color[v]].push_back(v); mate[v] = V; }
while (bfs(V)) for (int v : type[0]) if (mate[v] == V && dfs(V, v)) cardinality++;
return cardinality;
}
void dfsVertexCover(int v) {
if (vis[v]) return;
vis[v] = true;
for (int w : adj[v]) if ((mate[v] == w) == color[v]) dfsVertexCover(w);
}
void getVertexCover(int V) {
fill(vis, vis + V, false);
for (int v : type[0]) if (mate[v] == V) dfsVertexCover(v);
for (int v = 0; v < V; v++) inCover[v] = vis[v] == color[v];
}
};
const int MAXNM = 505;
int N, M;
string G[MAXNM];
HopcroftKarpMaxMatch<MAXNM * MAXNM * 2> mm;
int getUp(int i, int j) {
if (G[i][j] == '1') return i * M + j;
return getUp(i - 1, j);
}
int getLeft(int i, int j) {
if (G[i][j] == '1') return N * M + i * M + j;
return getLeft(i, j - 1);
}
int main() {
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
// freopen("err.txt", "w", stderr);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N >> M;
mm.init(N * M * 2);
fill(mm.color, mm.color + N * M, true);
for (int i = 0; i < N; i++) cin >> G[i];
for (int i = 0; i < N; i++) for (int j = 0; j < M; j++) if (G[i][j] == '0') mm.addEdge(getUp(i, j), getLeft(i, j));
cout << mm.getMaxMatch(N * M * 2) << nl;
mm.getVertexCover(N * M * 2);
for (int i = 0; i < N; i++) for (int j = 0; j < M; j++) if (G[i][j] == '1') {
if (mm.inCover[i * M + j] && mm.mate[i * M + j] != -1) cout << i + 1 << sp << j + 1 << sp << "DOLJE" << nl;
if (mm.inCover[N * M + i * M + j] && mm.mate[N * M + i * M + j] != -1) cout << i + 1 << sp << j + 1 << sp << "DESNO" << nl;
}
return 0;
}
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