题意：输入n个点m条边的联通图，n为奇数，设k为最小的奇数，使得每个点的度数不超过k，要求把节点都涂上颜色，使得相邻节点颜色不一样。

思路：dfs。k的值为奇数，所以k为节点最大度数（+1）。从当前节点往下找，如果下边的节点没有染色，就把当前节点染色继续下找。

code：

#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <sstream>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>using namespace std;typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;const int INF=0x3fffffff;
const int inf=-INF;
const int N=10005;
const int M=2005;
const int mod=1000000007;
const double pi=acos(-1.0);#define cls(x,c) memset(x,c,sizeof(x))
#define cpy(x,a) memcpy(x,a,sizeof(a))
#define fr(i,s,n) for (int i=s;i<=n;i++)
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define lrt  rt<<1
#define rrt  rt<<1|1
#define middle int m=(r+l)>>1
#define lowbit(x) (x&-x)
#define pii pair<int,int>
#define mk make_pair
#define IN freopen("in.txt","r",stdin);
#define OUT freopen("out.txt","w",stdout);int s[N],vis[N];
vector<int>g[N];
int k,n,m;void dfs(int u)
{cls(vis,0);vector<int>ne;for (int i=0;i<g[u].size();++i){int v=g[u][i];if (s[v]) vis[s[v]]=1;else ne.push_back(v);}for (int i=1;i<=k;i++){if (!vis[i]) {s[u]=i;break;}}for (int i=0;i<ne.size();i++){if (!s[ne[i]]) dfs(ne[i]);}
}
int main()
{int a,b,ca=0;while (~scanf("%d %d",&n,&m)){if (ca++) puts("");for (int i=0;i<n;i++) g[i].clear();for (int i=0;i<m;i++){scanf("%d %d",&a,&b);g[a-1].push_back(b-1);g[b-1].push_back(a-1);}cls(s,0);k=-1;for (int i=0;i<n;i++) k=max(k,(int)g[i].size());if (k%2==0) k++;printf("%d\n",k);dfs(0);for (int i=0;i<n;i++) printf("%d\n",s[i]);}
}