uva 1613——K-Graph Oddity

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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]);    }}

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