HDU - 5952 Counting Cliques (dfs)

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <math.h>
using namespace std;
#define LL long long
#define fi first
#define se second
#define pb(a) push_back(a)
const int MAX_N = 1e2+7;
const LL mod = 1e9+7;
const int inf = 0x3f3f3f3f;
int N,M,T,S;
int ans;
vector<int> vec[MAX_N];
int mp[MAX_N][MAX_N];
void dfs(int pos,int *sta ,int num){
    if(num == S){
        ans ++;
        return ;
    }
    for(int i=0;i<vec[pos].size();i++){
        int t = vec[pos][i];
        bool f = true;
        for(int j=0;j<num;j++){
            if(mp[t][sta[j]] == 0){
                f = false;
                break;
            }
        }
        if(f){
            sta[num ++] = t;
            dfs(t,sta,num);
            sta[num-1] = 0;
            num --;
        }
    }
}
int main()
{
    cin>>T;
    while(T--)
    {
        ans = 0;
        for(int i=0;i<MAX_N;i++){
            vec[i].clear();
        }
        memset(mp,0,sizeof(mp));
        scanf("%d%d%d",&N,&M,&S);
        for(int i=0;i<M;i++){
            int a,b;
            scanf("%d%d",&a,&b);
            if(a > b) swap(a,b);
            vec[a].push_back(b);
            mp[a][b] = mp[b][a] = 1;
        }
        for(int i=1;i<=N;i++){
            int sta[MAX_N];
            sta[0] = i;
            dfs(i,sta,1);
        }
        printf("%d\n",ans);

    }
    return 0;
}