``` #include <bits/stdc++.h> using namespace std; int a[] = {1, 1, 2, 2, 3, 3, 4, 4}; int out[8]; bool ist[8], done; bool check() { bool ist_[5]; memset(ist_, false, sizeof ist_); for (int i = 0; i < 8; i ++) if (!ist_[1] && out[i] == 1) { for (int j = i + 1; j < 8; j ++) { if (out[j] == 1) { if (j - i - 1 != 1) return false; ist[1] = true; break; } } if (!ist_[2] && out[i] == 2) for (int j = i + 1; j < 8; j ++) { if (out[j] == 2) { if (j - i - 1 != 2) return false; ist[2] = true; break; } } if (!ist_[3] && out[i] == 3) for (int j = i + 1; j < 8; j ++) { if (out[j] == 3) { if (j - i - 1 != 3) return false; ist[3] = true; break; } } if (!ist_[4] && out[i] == 4) for (int j = i + 1; j < 8; j ++) { if (out[j] == 4) { if (j - i - 1 != 4) return false; ist[4] = true; break; } } } return true; } void dfs(int u) { if (done) return; if (u == 8) { if (check()) { for (int i = 0; i < 8; i ++) { if (out[i] == 1) cout << 'A'; else cout << out[i]; } puts(""); done = true; } return; } for (int i = 0; i < 8; i ++) { if (!ist[i]) { ist[i] = true; out[u] = a[i]; dfs(u + 1); ist[i] = false; } } } int main(void) { dfs(0); return 0; } ```

``` #include<iostream> #include<cstring> #include<algorithm> using namespace std; // int a[2]; int b[2]; int c[2]; int d[2]; int ans; bool check(string s) { int ia=0,ib=0,ic=0,id=0; for(int i=0;i<s.size();i++) { if(s[i]=='1')a[ia++]=i; if(s[i]=='2')b[ib++]=i; if(s[i]=='3')c[ic++]=i; if(s[i]=='4')d[id++]=i; } int cnta=0; for(int i=a[0];i<=a[1];i++)cnta++; if(cnta-2!=1)return false; int cntb=0; for(int i=b[0];i<=b[1];i++)cntb++; if(cntb-2!=2)return false; int cntc=0; for(int i=c[0];i<=c[1];i++)cntc++; if(cntc-2!=3)return false; int cntd=0; for(int i=d[0];i<=d[1];i++)cntd++; if(cntd-2!=4)return false; return true; } int arr[8]={1,1,2,2,3,3,4,4}; int main() { do{ string s=""; for(int i=0;i<8;i++)s+=arr[i]+'0'; if(check(s)) { cout<<s<<endl; return 0; } }while(next_permutation(arr,arr+8)); return 0; } //1--A --->2342A3A4 ```