。。。

类格雷码顺序生成分划…

某种基于递归的构造。

#include <iostream> #include <cstring> #include <vector> using namespace std; const int N = 100; int A[N], C[N]; string SS[N]; string S; int n; vector<string> res; void encode(){ /*for (int i=0;i<n;i++) cout << A[i] << " "; cout << endl; */ int m = 0; for (int i=0;i<n;i++) m = max(m, A[i]); for (int i=0;i<=m;i++) SS[i].clear(); S.clear(); for (int i=0;i<n;i++){ if (i==9) SS[A[i]] += "10"; else SS[A[i]] += char(i + 49); SS[A[i]] += ','; } for (int i=0;i<=m;i++){ SS[i].erase(SS[i].size()-1); S += "{", S += SS[i], S += "},"; } S.erase(S.size()-1); res.push_back(S); } void dfs(int k, int m){ if (k==n){ encode(); } else { if ((C[k]&1)==0){ for (int i=0;i<=m;i++) A[k] = i, dfs(k+1, m); A[k] = m+1, dfs(k+1, m+1); } else { A[k] = m+1, dfs(k+1, m+1); for (int i=m;i>=0;i--) A[k] = i, dfs(k+1, m); } C[k]++; } } int main(){ while (cin >> n){ res.clear(); memset(C, 0, sizeof(C)); dfs(1, 0); cout << res.size() << endl; for (int i=0;i<res.size();i++) cout << res[i] << endl; } }