深搜——数字划分问题

 1 #include<iostream>
 2 using namespace std;
 3 int n,ans[20],acc;
 4 void judge(){
 5     int sign = 1;
 6     int now = 0;
 7     int next = 1;
 8     for(int i = 1;i < n;i++){
 9         if(ans[i] == 3){
10             next = next * 10 + (i+1);
11         }else{
12             if(sign == 1) now += next;
13             if(sign == 2) now -= next;
14             if(ans[i] == 1) sign = 1;
15             if(ans[i] == 2) sign = 2;
16             next = i + 1;
17         }
18     }
19     if(sign == 1) now += next;
20     if(sign == 2) now -= next;
21     if(!now){
22         for(int i = 1;i < n;i++){
23             cout<<i;
24             if(ans[i] == 1) cout<<"+";
25             if(ans[i] == 2) cout<<"-";
26             if(ans[i] == 3) cout<<" ";
27         }
28         cout<<n<<endl;
29     }
30 }
31 int dfs(int deep){
32     if(deep == n){
33         judge();
34         return 0;
35     }
36     ans[deep] = 3;
37     dfs(deep+1);
38     ans[deep] = 1;
39     dfs(deep+1);
40     ans[deep] = 2;
41     dfs(deep+1);
42 }
43 int main(){
44     cin>>n;
45     dfs(1);
46     return 0;
47 }