USACO milk3 DFS

/*ID:kevin_s1PROG:milk3LANG:C++*/#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>using namespace std;int A,B,C;int milk[21][21][21];int note[21];void DFS(int a, int b, int c){if(milk[a][b][c] == 1)return;milk[a][b][c] = 1;if(a == 0){note[c] = 1;}//A to Bif(a + b <= B){DFS(0, a + b, c);}else{DFS(a + b - B, B, c);}//A to Cif(a + c <= C){DFS(0, b, a + c);}else{DFS(a + c - C, b, C);}//B to Aif(b + a <= A){DFS(a + b, 0, c);}else{DFS(A, a + b - A, c);}//B to Cif(b + c <= C){DFS(a, 0, b + c);}else{DFS(a, b + c - C, C);}//C to Aif(c + a <= A){DFS(c + a, b, 0);}else{DFS(A, b, a + c - A);}//C to Bif(c + b <= B){DFS(a, b + c, 0);}else{DFS(a, B, b + c - B);}return;}int main(){freopen("milk3.in","r",stdin);freopen("milk3.out","w",stdout);memset(note,0,sizeof(note));memset(milk,0,sizeof(milk));cin>>A>>B>>C;DFS(0, 0, C);bool flag = false;for(int i = 0; i <=20; i++){if(note[i] == 1 && flag){cout<<" ";}if(note[i]){cout<<i;flag = true;}}cout<<endl;return 0;}