邻接矩阵版

int n;
int d[N][N], match[N];
bool st[N];

bool find(int x)
{
    for (int j = 1; j <= n; j ++ )
    {
        if (d[x][j] && !st[j])
        {
            st[j] = true;
            if (match[j] == 0 || find(match[j]))
            {
                match[j] = x;
                return true;
            }
        }
    }

    return false;
}

...

int cnt = 0;
for (int i  = 1; i <= n; i ++ )
{
    memset(st, false, sizeof st);
    if (find(i)) cnt ++;
}

邻接表版

int n;
int h[N], e[M], ne[M], idx;
int match[N];
bool st[N];

void add(int a, int b)
{
    e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}
bool find(int x)
{
    for (int i = h[x]; i != -1; i = ne[i])
    {
        int j = e[i];
        if (!st[j])
        {
            st[j] = true;
            if (match[j] == 0 || find(match[j]))
            {
                match[j] = x;
                return true;
            }
        }
    }

    return false;
}

...

for (int i  = 1; i <= n; i ++ )
{
    memset(st, false, sizeof st);
    if (find(i)) cnt ++;
}