Hopcroft-Karp Algorithm Template

#include <cstdio>#include <cstring>#include <vector>#include <queue>#include <stack>#include <cmath>using namespace std;const int maxn = 3010;const int INF = 1<<28;int dx[maxn], dy[maxn];int cx[maxn], cy[maxn];vector <int> G[maxn];int dis;int n, m;bool vis[maxn];bool search(){queue <int> Q;int dis = INF;memset(dx, -1, sizeof(dx));memset(dy, -1, sizeof(dy));for(int i = 0; i < n; i++)if(cx[i] == -1){Q.push(i);dx[i] = 0;}while(!Q.empty()){int u = Q.front(); Q.pop();if(dx[u] > dis)break;for(int i = 0; i < G[u].size(); i++){int v = G[u][i];if(dy[v] == -1){dy[v] = dx[u] + 1;if(cy[v] == -1)dis = dy[v];else{dx[cy[v]] = dy[v] + 1;Q.push(cy[v]);}}}}return dis != INF;}bool dfs(int u){for(int i = 0; i < G[u].size(); i++){int v = G[u][i];if(vis[v])continue;vis[v] = true;if(dy[v] == dx[u]+1){if(cy[v] != -1 && dy[v] == dis)continue;if(cy[v] == -1 || dfs(cy[v])){cy[v] = u;cx[u] = v;return true;}}}return false;}int match(){    int ans = 0;    memset(cx, -1, sizeof(cx));    memset(cy, -1, sizeof(cy));    while(search())    {memset(vis, 0, sizeof(vis));for(int i = 0; i < n; i++)if(cx[i] == -1 && dfs(i))    ans++;    }    return ans;}