算法 BISHI29 小红的排列构造① 求解代码 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StreamTokenizer in = new StreamTokenizer(br); PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out)); in.nextToken(); int n = (int) in.nval; int[] arr = new int[n]; if(n<=2){ out.println(-1); }else{ arr[0]=3;// 第一个元素固定为3 for (int i = 1; i < n; i++) { arr[i]=i+1;//从第2个元素开始,值为「索引+1」 } arr[2]=1;// 第三个元素强制改为1 for(int i=0;i<n;i++){ out.print(arr[i]+(i == n - 1 ? "" : " ")); } } out.flush(); out.close(); br.close(); }