二分图匹配——Hopcroft-Carp算法模板

typedef long long LL;
using namespace std;
const int maxn = 3010;
const int INF = 0x3f3f3f3f;
bool g[maxn][maxn];
bool vis[maxn];
int dx[maxn],dy[maxn];
int Mx[maxn],My[maxn];
int dis;
int GM[maxn][2];
int GN[maxn][2];
int speed[maxn];
double _time;
int M,N;

bool bfs(int n,int m)
{
dis = INF;
memset(dx,-1,sizeof(dx));
memset(dy,-1,sizeof(dy));
queue <int> que;
for(int i = 0; i < n; i++)
{
if(Mx[i] == -1)
{
que.push(i);
dx[i] = 0;
}
}

while(!que.empty())
{
int u = que.front();
que.pop();
if(dx[u] > dis)  break;
for(int v = 0; v < m; v ++)
{
if(g[u][v] && dy[v] == -1)
{
dy[v] = dx[u] + 1;
if(My[v] == -1) dis = dy[v];
else {
dx[My[v]] = dy[v] + 1;
que.push(My[v]);
}
}
}
}
return dis != INF;
}

bool dfs(int u,int m)
{
for(int v = 0; v < m; v++)
{
if(g[u][v] && !vis[v] && dy[v] == dx[u] + 1)
{
vis[v] = true;
if(My[v] != -1 && dy[v] == dis) continue;

if(My[v] == -1 || dfs(My[v],m))
{
My[v] = u;
Mx[u] = v;
return true;
}
}
}
return false;
}

int Max_match(int n,int m)
{
int all = 0;
memset(Mx,-1,sizeof(Mx));
memset(My,-1,sizeof(My));
while(bfs(n,m))
{
memset(vis,false,sizeof(vis));
for(int i = 0; i < n; i++)
if(Mx[i] == -1 && dfs(i,m))
all++;
}
return all;
}