LA 3231 Fair Shar

#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int INF = 0x3f3f3f3f;
struct node{
	int to,next,flow;
}e[2000010];
int a[100010],b[100010],d[100010];
int S,T;
int head[100010],cnt,cur[100010];
void add_edge(int from,int to,int flow){
	e[cnt].to = to;
	e[cnt].flow = flow;
	e[cnt].next = head[from];
	head[from] = cnt++;
	
	e[cnt].to = from;
	e[cnt].flow = 0;
	e[cnt].next = head[to];
	head[to] = cnt++; 
}
int bfs(){
	memset(d,0,sizeof(d));
	queue<int>q;
	q.push(S);
	d[S] = 1;
	while(!q.empty()){
		int u = q.front();
		q.pop();
		for(int i = head[u]; i != -1; i = e[i].next){
			int v = e[i].to;
			if(!d[v] && e[i].flow){
				d[v] = d[u] + 1;
				if(v == T) return 1;
				q.push(v);
			}
		}
	}
	return 0;
}
int dfs(int u,int flow){
	int cost = 0;
	if(u == T) return flow;
	for(int &i = cur[u]; i != -1; i = e[i].next){
		int v = e[i].to;
		if(d[v] == d[u] + 1 && e[i].flow){
			int t =dfs(v,min(flow - cost,e[i].flow));
			if(t){
				e[i].flow -= t;
				e[i^1].flow += t;
				cost += t;
				if(flow == cost) break;
			}
		}
	}
	return cost;
}
int Dinic(){
	int res = 0;
	while(bfs()){
		for(int i = 0; i <= T; i++) cur[i] = head[i];
		res += dfs(S,INF);
	}
	return res;
}
int main(){
	int t,n,m;
	scanf("%d",&t);
	while(t--){
		scanf("%d%d",&n,&m);
		for(int i = 1; i <= m; i++) scanf("%d%d",&a[i],&b[i]);
		int l = 1,r = m;
		S = 0; T = n + m + 1;
		while(l < r){
	//		printf("l = %d  r = %d\n",l,r);
			int M = (l + r) / 2;
			for(int i = 0; i <= T; i++) head[i] = -1;
			cnt = 0;
			for(int i = 1; i <= m; i++) add_edge(0,i,1);
			for(int i = 1; i <= m; i++){
				add_edge(i,m + a[i],1);
				add_edge(i,m + b[i],1);
			}
			for(int i = 1; i <= n; i++){
				add_edge(m + i, T, M);
			}
			int t = Dinic();
			if(t >= m){
				r = M;
			}else l = M + 1;
		}
		printf("%d\n",l);
	}
	return 0;
}