POJ 1129

相邻定点不能为一种频道，转化为图定点的着色问题。

/*
8737793 MDK 1129 Accepted 692K 0MS G++ 1858B 2011-06-08 09:40:42 
*/
#include<stdio.h>
#include<iostream>
#include<limits.h>

#include<string.h>
#include<math.h>
#include<time.h>

#include<vector>
#include<list>
#include<algorithm>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<deque>

using namespace std;

#define MAXN 26
#define MAXNT 5050
#define LL(x) ((x)<<1)
#define RR(x) ((x)<<1|1)
#define F(i,n) for(int i = 0 ; i < n ; i ++)
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define DB(a) cout<<a<<endl
#define PP(n,m,a)            puts("---");F(i,n){F(j,m)cout << a[i][j] << ' ';puts("-");}puts("---");
#define SET(a,what) memset(a,what,sizeof(a))
#define SETQ(que) while(!que.empty()) que.pop();
#define SCF(x) scanf("%d",&x)
#define SCFD(x,y) scanf("%d%d",&x,&y)
#define SCFT(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define SCFC(x) scanf("%c",&x)
#define SCFS(x) scanf("%s",x)
#define PCFLN(x) printf("%d\n",x)
#define PCF(x) printf("%d",x)
#define PF(x) printf(x)
int mat[MAXN][MAXN],c[MAXN],b[MAXN],ans=0;
void greedy(int n)
{
    int k;
    F(i,n)
    {
        SET(b,0);
        for(k=0;k<n;k++)
            if(mat[i][k]&&c[k]!=-1)
                b[c[k]]=1;
        for(k=0;k<n;k++)
            if(!b[k]) break;
        c[i]=k;
    }
    F(i,n)
        if(ans<c[i]) ans=c[i];
    ans++;
}
int main()
{
    int n;char ss[27],sc;

    while(SCF(n)!=EOF&&n)
    {
        int len;ans=0;
        SET(ss,'\0');SET(mat,0);SET(c,-1);
        F(i,n)
        {
            SCFS(ss);
            len=strlen(ss);
            if(len!=2)
                FOR(j,2,len-1)
                {
                    mat[ss[0]-'A'][ss[j]-'A']=mat[ss[j]-'A'][ss[0]-'A']=1;
                }
        }
        //PP(n,n,mat);
        greedy(n);
        if(ans!=1) printf("%d channels needed.\n",ans);
        else printf("%d channel needed.\n",ans);
    }
}

其实就是种贪心。