BFS 版本的匈牙利算法

#include<iostream>#include<vector>#include<unordered_set>#include<queue>#include<stack>#include<cstring>#include<queue>using namespace std;int hungry_bfs(vector<vector<int> >& bi_graph, int m, vector<int>& match) {    int n = bi_graph.size();    match.clear();    match.resize(m, -1);    int ret = 0;    for (int i = 0; i < n; ++i) {        unordered_set<int> visited;   //记录访问过的右节点        vector<int> match_tmp(n, -1); //试探性匹配:l->r        queue<int> Q;                 //试探顺序控制队列        Q.push(i);        stack<int> S;                 //记录试探性匹配的左节点的顺序        bool ext = false;        while (!Q.empty() && !ext) {            int c = Q.front();            Q.pop();            for (int adj : bi_graph[c]) {                if (visited.count(adj) != 0) continue;                if (match[adj] == -1) {                    //构造增广链                     match_tmp[c] = adj;                     S.push(c);                     while (!S.empty()) {                         int cc = S.top();                         S.pop();                         match[match_tmp[cc]] = cc;                     }                     match_tmp.clear();                     ext = true;                     break;                } else {                    visited.insert(adj);                    Q.push(match[adj]);                    match_tmp[c] = adj;                    S.push(c);                }            }            if (ext) {                ret += 1;            }        }    }    return ret;}int main() {    int n, m;    cin>>n>>m;    int ne;    cin>>ne;    vector<vector<int> > bi_graph(n, vector<int>());    for (int i = 0; i < ne; ++i) {        int l, r;        cin>>l>>r;        bi_graph[l].push_back(r);    }    vector<int> match;    int ret = hungry_bfs(bi_graph, m, match);    cout<<ret<<endl;    return 0;}