hdu 3018 Ant Trip

#include<cstdio>
#include<iostream>

using namespace std;

#define N 100001
#define M 200001

int fa
;

int sum
,d
;
int odd
;

struct node
{
int u,v;
}e[M];

void read(int &x)
{
x=0; char c=getchar();
while(!isdigit(c)) c=getchar();
while(isdigit(c)) { x=x*10+c-'0'; c=getchar();}
}

int find(int i) { return fa[i]==i ? i : fa[i]=find(fa[i]); }

int main()
{
int n,m,u,v;
int ans;
while(scanf("%d",&n)!=EOF)
{
read(m);
for(int i=1;i<=m;++i) read(e[i].u),read(e[i].v);
for(int i=1;i<=n;++i) fa[i]=i,sum[i]=1,odd[i]=d[i]=0;
for(int i=1;i<=m;++i)
{
d[e[i].u]++;
d[e[i].v]++;
u=find(e[i].u);
v=find(e[i].v);
if(u!=v) sum[v]+=sum[u],fa[u]=v;
}
ans=0;
for(int i=1;i<=n;++i)
if(d[i]&1) odd[find(i)]++;
for(int i=1;i<=n;++i)
if(find(i)==i && d[i])
{
if(!odd[i]) ans++;
else ans+=odd[i]/2;
}
printf("%d\n",ans);
}
}