50243. Friend Cover

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
 
int n, m;
int f[512][2];
 
int check(int arr[], int arr_size){
    int have[64] = {0};
    for(int i = 0; i < arr_size; i++) have[arr[i]] = 1;
    for(int i = 0; i < m; i++){
        if(!have[f[i][0]] && !have[f[i][1]]) return 0;
    }
    return 1;
}
 
int min_num = 128;
int min_arr[64];
void dfs(int arr[], int arr_size, int now_idx, int n){
    if(arr_size >= min_num) return;
    if(now_idx == n){
        if(!check(arr, arr_size)) return;
        else{
            min_num = arr_size;
            for(int i = 0; i < arr_size; i++) min_arr[i] = arr[i];
        }
    }
    else{
        // choose
        arr[arr_size] = now_idx;
        dfs(arr, arr_size + 1, now_idx + 1, n);
 
        // no choose
        arr[arr_size] = 0;
        dfs(arr, arr_size, now_idx + 1, n);
    }
}
 
int main(){
    scanf("%d %d", &n, &m);
    for(int i = 0; i < m; i++){
        scanf("%d %d", &f[i][0], &f[i][1]);
    }
 
    int arr[64];
    dfs(arr, 0, 0, n);
    for(int i = 0; i < min_num; i++) printf("%d\n", min_arr[i]);
}