Codeforces Round #588 (Div. 2) Anadi and Domino （dfs）

题目链接：https://codeforces.com/contest/1230/problem/C

 思路：暴搜，，，，赛后一遍过，为啥当时没想到。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<ctime>
 4 #include<cstring>
 5 #include<cstdlib>
 6 #include<cmath>
 7 #include<queue>
 8 #include<stack>
 9 #include<map> 
10 #include<algorithm>
11 #define Max(a,b) ((a)>(b)?(a):(b))
12 #define Min(a,b) ((a)<(b)?(a):(b))
13 #define Mem0(x) memset(x,0,sizeof(x))
14 #define Mem1(x) memset(x,-1,sizeof(x))
15 #define MemX(x) memset(x,0x3f,sizeof(x))
16 using namespace std;
17 typedef long long ll;
18 const int inf=0x3f3f3f;
19 const double pi=acos(-1.0);
20 
21 int cnt[30][30];
22 struct node{
23     int x,y;
24     bool flag;
25 }edge[30];
26 
27 void init()
28 {
29     memset(cnt,0,sizeof(cnt));
30     for (int i=1;i<=6;i++){
31         for (int j=i;j<=6;j++){
32             cnt[i][j]++;
33         }
34     }
35     return ;
36 }
37 int node1[20],n,m,ans;
38 void dfs()
39 {
40     init();
41     node edge1[30];
42     for (int i=1;i<=m;i++){
43         edge1[i].x=edge[i].x;
44         edge1[i].y=edge[i].y;
45         edge1[i].flag=false;
46     } 
47     int tmp=0;
48     for (int i=1;i<=m;i++){
49         if (cnt[node1[edge1[i].x]][node1[edge1[i].y]]>0){
50             cnt[node1[edge1[i].x]][node1[edge1[i].y]]--;
51             tmp++;
52         }
53     }
54     ans=max(tmp,ans);
55     return ;
56 }
57 void find(int pos)
58 {
59     if (pos==n+1){
60         dfs();
61         return ;
62     }
63     for (int i=1;i<=6;i++){
64         node1[pos]=i;
65         find(pos+1);
66     }
67     return ;
68 }
69 int main()
70 {
71     ans=0;
72     cin>>n>>m;
73     for (int i=1;i<=m;i++){
74         cin>>edge[i].x>>edge[i].y;
75         if (edge[i].x>edge[i].y){
76             int temp=edge[i].x;
77             edge[i].x=edge[i].y;
78             edge[i].y=temp;
79         }
80     }
81     find(0);
82     cout<<ans<<endl;
83     return 0;
84 }