Ant Trip(欧拉回路+并查集)

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#define rep(i,a,b) for(int i=a;i<=b;i++)
using namespace std;
int n,m,fa[100040],de[100004],sum[100040],num[100004];
void init(){
	memset(de,0,sizeof(de));
	memset(sum,0,sizeof(sum));
	memset(num,0,sizeof(num));
	rep(i,1,n) fa[i]=i;
}
int find(int x){
	if(fa[x]==x) return x;
	else return fa[x]=find(fa[x]);
}
int main(){
	freopen("1.txt","r",stdin)	while(~scanf("%d%d",&n,&m)){
		int s=0;
		init();
		rep(i,1,m){
			int a,b; 
			scanf("%d%d",&a,&b);
			++de[a]; ++de[b];
			a=find(a); b=find(b);
			if(a!=b) fa[a]=b;
		}
		rep(i,1,n){
			if(de[i]&1) sum[find(i)]++;
			num[find(i)]++;
		} 
		rep(i,1,n){
			if(num[i]==0 || num[i]==1) continue;
			else if(sum[i]==0) ++s;
			else s+=(sum[i]/2);
		}
		printf("%d\n",s);
	}
	return 0;
}