Graph Coloring

#include<bits/stdc++.h>

using namespace std;

bool graph[110][110];

bool color[110],ans[110];

int node,edge,curr;

bool yes(int n)
{
    for(int i=1; i<=node; i++)
    {
        if(graph[n][i] && color[i])
        {
            return false;
        }
    }

    return true;
}

void dfs(int n,int mx)
{
    if(n==node+1)
    {
        if(curr<mx)
        {
            curr = mx;

            memcpy(ans,color,sizeof(color));
        }

        return;
    }

    if(yes(n))
    {
        color[n] = true;

        dfs(n+1,mx+1);

        color[n] = false;
    }

    dfs(n+1,mx);
}

int main()
{
    int test,i,u,v;

    scanf("%d",&test);

    while(test--)
    {
        scanf("%d%d",&node,&edge);

        for(i=1; i<=edge; i++)
        {
            scanf("%d%d",&u,&v);

            graph[u][v] = graph[v][u] = true;
        }

        curr = 0;

        dfs(1,0);

        printf("%d\n",curr);

        for(i=1;i<=node;i++)
        {
            if(ans[i])
            {
                printf("%d",i);

                break;
            }
        }

        for(i=i+1;i<=node;i++)
        {
            if(ans[i])
            {
                printf(" %d",i);
            }
        }

        puts("");

        memset(color,false,sizeof(color));

        memset(graph,false,sizeof(graph));

    }

    return 0;
}