CPP

#include <iostream>
#include <vector>
#include <cstring>
using namespace std;
#define VI vector<int>
#define pb push_back

#define NMAX 100000

int l[NMAX], r[NMAX];
VI G[NMAX];
bool visited[NMAX];
int n,m,e,x,y,rs;

bool dfs(int v) {
    if(visited[v]) { return 0; }
    visited[v]=1;
    for(auto w:G[v]) {
        if(l[w] == 0 || dfs(l[w])) {
            l[w]=v;
            r[v]=w;
            return 1;
        }
    }
    return 0;
}

int main() {
    cin>>n>>m>>e;
    for(int i=1; i<=e; ++i) {
        cin>>x>>y;
        G[x].pb(y+n);
    }
    bool q=1;
    while(q) {
        q=0;
        memset(visited, 0, sizeof(visited));
        for(int i=1; i<=n; ++i) {
            if(r[i]==0 && dfs(i)) {
                q=1;
                rs++;
            }
        }
    }
    cout<<rs<<"\n";
}

Java

import java.util.*;
import java.util.stream.*;
import java.io.*;
import java.math.*;
import java.awt.geom.*;
public class testNode {
  public static BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in));
  public static StringTokenizer tokenizer = null;
  public static String nextLine() {
    try { return buffer.readLine(); } catch (Exception e) { throw new RuntimeException(e); }
  }
  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreElements()) {
      tokenizer = new StringTokenizer(nextLine());
    }
    return tokenizer.nextToken();
  }
  public static int nextInt() { return Integer.parseInt(next()); }
  public static long nextLong() { return Long.parseLong(next()); }
  public static double nextDouble() { return Double.parseDouble(next()); }
  public static final Node[] as = new Node[50000];
  public static final Node[] bs = new Node[50000];
  public static final boolean[] visited = new boolean[50000];
  public static void main(String[] args) {
    final int n = nextInt(), m = nextInt(), e = nextInt();
    for (int i = 0; i < n; i++) { as[i] = new Node(i); }
    for (int i = 0; i < n; i++) { bs[i] = new Node(i); }
    for (int i = 0; i < e; i++) {
      final int x = nextInt()-1, y = nextInt()-1;
      as[x].adj.add(bs[y]);
    }
    boolean flag=true;
    int out = 0;
    while (flag) {
      flag = false;
      Arrays.fill(visited, false);
      for (int i = 0; i < n; i++) {
        if (as[i].match == null && dfs(as[i])) {
          flag = true;
          out++;
        }
      }
    }
    System.out.println(out);
  }
  public static boolean dfs(Node n) {
    if(visited[n.ndx]) { return false; }
    visited[n.ndx] = true;
    for (Node w : n.adj) {
      if(w.match == null || dfs(w.match)) {
        w.match=n;
        n.match=w;
        return true;
      }
    }
    return false;
  }
  public static class Node {
    public ArrayList<Node> adj = new ArrayList<Node>();
    public Node match = null;
    public int ndx;
    public int ndx() { return ndx; }
    Node(int ndx_) { ndx=ndx_; }
  }
}