UVa 193 - Graph Coloring

回溯，枚举所有点的黑白情况，然后判断可行性。

代码如下：

#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
int map[102][102], node[102], save[101], n, k, cct;
int judge(int cur)
{
    for(int i = 1; i <= n; i++)
        if(map[cur][i] && node[i])
            return 0;
    return 1;
}
void DFS(int cur)
{
    if(cur == n + 1)
    {
        int ct = 0;
        for(int i = 1; i <= n; i++)
            if(node[i])
                ++ct;

        if(ct > cct)
        {
            cct = ct;
            for(int i = 1, j = 0; i <= n; i++)
                if(node[i])
                {
                    save[j] = i;
                    ++j;
                }
        }
        return ;
    }
    node[cur] = 0;
    DFS(cur + 1);
    node[cur] = 1;
    if(judge(cur))
        DFS(cur + 1);
    node[cur] = 0;
}
int main()
{
#ifdef test
    freopen("sample.txt", "r", stdin);
#endif
    int m, x, y;
    scanf("%d", &m);
    while(m--)
    {
        cct = 0;
        scanf("%d%d", &n, &k);
        memset(map, 0, sizeof(map));
        for(int i = 0; i < k; i++)
        {
            scanf("%d%d", &x, &y);
            map[x][y] = map[y][x] = 1;
        }
        DFS(1);
        printf("%d\n%d", cct, save[0]);
        for(int i = 1; i < cct; i++)
            printf(" %d", save[i]);
        puts("");
    }
    return 0;
}