HDU 5348 MZL's endless loop

#include<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#include<algorithm>
using namespace std;

const int maxn=100000;
int n,m;
struct Edge
{
    int from,to;
    int ans;
    int flag;
} edge[3*maxn+10];
vector<int> G[maxn+10];
int tot[maxn+10];
int Ru[maxn+10];
int Ch[maxn+10];
int St[maxn+10];

void dfs(int now,int x)
{
    for(int i=St[now]; i<G[now].size(); i++)
    {
        Edge &e=edge[G[now][i]];
        if(!e.flag)//这条边没走过
        {
            St[now]=i+1;
            if(x==1)
            {
                if(e.from==now)
                {
                    e.ans=1;
                    e.flag=1;
                    tot[e.from]--;
                    tot[e.to]--;
                    Ch[e.from]++;
                    Ru[e.to]++;
                    dfs(e.to,x);
                    return;

                }
                else if(e.to==now)
                {
                    e.ans=0;
                    e.flag=1;
                    tot[e.from]--;
                    tot[e.to]--;
                    Ch[e.to]++;
                    Ru[e.from]++;
                    dfs(e.from,x);
                    return;
                }
            }
            else if(x==0)
            {
                if(e.to==now)
                {
                    e.ans=1;
                    e.flag=1;
                    tot[e.from]--;
                    tot[e.to]--;
                    Ru[e.to]++;
                    Ch[e.from]++;
                    dfs(e.from,x);
                    return;
                }
                else if(e.from==now)
                {
                    e.ans=0;
                    e.flag=1;
                    tot[e.from]--;
                    tot[e.to]--;
                    Ru[e.from]++;
                    Ch[e.to]++;
                    dfs(e.to,x);
                    return;
                }
            }
        }
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    for(int y=1; y<=T; y++)
    {
        scanf("%d%d",&n,&m);
        for(int i=0; i<=n; i++) G[i].clear();
        memset(tot,0,sizeof(tot));
        memset(Ru,0,sizeof(Ru));
        memset(Ch,0,sizeof(Ch));
        memset(St,0,sizeof(St));
        for(int i=1; i<=m; i++)
        {
            scanf("%d%d",&edge[i].from,&edge[i].to);
            if(edge[i].from==edge[i].to)
            {
                edge[i].ans=1;
                continue;
            }
            edge[i].flag=0;
            G[edge[i].from].push_back(i);
            G[edge[i].to].push_back(i);
            tot[edge[i].from]++;
            tot[edge[i].to]++;
        }
        for(int i=1; i<=n; i++)
        {
            while(tot[i])
            {
                if(Ru[i]>=Ch[i]) dfs(i,1);
                else dfs(i,0);
            }
        }
        for(int i=1; i<=m; i++)
            printf("%d\n",edge[i].ans);
    }
    return 0;
}