BISHI29 小红的排列构造①

求解代码

publicstaticvoidmain(String[]args)throwsIOException{BufferedReaderbr=newBufferedReader(newInputStreamReader(System.in));StreamTokenizerin=newStreamTokenizer(br);PrintWriterout=newPrintWriter(newOutputStreamWriter(System.out));in.nextToken();intn=(int)in.nval;int[]arr=newint[n];if(n<=2){out.println(-1);}else{arr[0]=3;// 第一个元素固定为3for(inti=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1for(inti=0;i<n;i++){out.print(arr[i]+(i==n-1?"":" "));}}out.flush();out.close();br.close();}