图论 HDOJ 5348 MZL's endless loop

题目传送门

 /*
     题意：给一个n个点,m条边的无向图,要求给m条边定方向,使得每个定点的出入度之差的绝对值小于等于1. 输出任意一种结果
     图论：一个图，必定存在偶数个奇度顶点。那么从一个奇度定点深搜，当碰到另外一个奇度顶点时结束，这样能保证度数差<=1
 3.5　 详细解释：http://blog.csdn.net/ZSGG_ACM/article/details/47287681　　
 */
 /************************************************
  * Author        :Running_Time
  * Created Time  :2015-8-5 18:55:37
  * File Name     :F.cpp
  ************************************************/
 #pragma comment (linker, "/STACK:1024000000,1024000000")
 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef long long ll;
 const int MAXN = 1e5 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 struct Edge {
     int v, nex, dir;
 }e[MAXN*];
 int head[MAXN];
 int deg[MAXN];
 int n, m, tot;

 void init(void) {
     tot = ;
     memset (head, -, sizeof (head));
     memset (deg, , sizeof (deg));
 }

 void add_edge(int u, int v) {
     e[tot].v = v;
     e[tot].nex = head[u];
     e[tot].dir = ;
     head[u] = tot++;
 }

 bool DFS(int u) {
     for (int &i=head[u]; ~i; i=e[i].nex)    {
         int v = e[i].v;
         int dir = e[i].dir ^ e[i^].dir;
         if (dir)    continue;
         e[i].dir = ;
         if (deg[v]) {
             deg[v] = ; return true;
         }
         if (DFS (v))    return true;
     }
     return false;
 }

 void work(void) {
     for (int i=; i<=n; ++i)    {
         if (deg[i]) {
             deg[i] = ; DFS (i);
         }
     }
     for (int i=; i<=n; ++i)    {
         while (~head[i])    DFS (i);
     }
     for (int i=; i<tot; i+=)  {
         if (e[i].dir)   puts ("");
         else    puts ("");
     }
 }

 int main(void)    {     //HDOJ 5348 MZL's endless loop
     int T;  scanf ("%d", &T);
     while (T--) {
         init ();
         scanf ("%d%d", &n, &m);
         for (int i=; i<=m; ++i)    {
             int u, v;   scanf ("%d%d", &u, &v);
             deg[u] ^= ;   deg[v] ^= ;
             add_edge (u, v);    add_edge (v, u);
         }
         work ();
     }

     return ;
 }

 /************************************************
  * Author        :Running_Time
  * Created Time  :2015-8-5 18:55:37
  * File Name     :F.cpp
  ************************************************/
 #pragma comment (linker, "/STACK:1024000000,1024000000")
 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef long long ll;
 const int MAXN = 1e5 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 struct Edge {
     int v, nex, vis;
 }e[MAXN*];
 int head[MAXN];
 int deg[MAXN];
 int ans[MAXN*];
 int n, m, tot;

 void init(void) {
     tot = ;
     memset (head, -, sizeof (head));
     memset (deg, , sizeof (deg));
 }

 void add_edge(int u, int v) {
     e[tot].v = v;
     e[tot].nex = head[u];
     e[tot].vis = ;
     head[u] = tot++;
 }

 void DFS(int u) {
     for (int &i=head[u]; ~i; )    {
         int v = e[i].v;
         if (e[i].vis)   {
             i = e[i].nex;   continue;
         }
         e[i].vis = ;   e[i^].vis = ;
         ans[i>>] = i & ;
         deg[u]--;   deg[v]--;
         i = e[i].nex;
         DFS (v);
     }
 }

 void patch(void) {
     int pre = -;
     for (int i=; i<=n; ++i)    {
         if (deg[i] & ) {
             if (pre == -)  {
                 pre = i;
             }
             else    {
                 add_edge (pre, i);  add_edge (i, pre);
                 deg[pre]++; deg[i]++;
                 pre = -;
             }
         }
     }
 }

 void work(void) {
     patch ();
     for (int i=; i<=n; ++i)    {
         if (deg[i]) DFS (i);
     }
     for (int i=; i<m; ++i)    printf ("%d\n", ans[i]);
 }

 int main(void)    {
     int T;  scanf ("%d", &T);
     while (T--) {
         init ();
         scanf ("%d%d", &n, &m);
         for (int i=; i<=m; ++i)    {
             int u, v;   scanf ("%d%d", &u, &v);
             deg[u]++;   deg[v]++;
             add_edge (u, v);    add_edge (v, u);
         }
         work ();
     }

     return ;
 }

不太清楚的代码