由中序遍历和后序遍历 输出先序遍历
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
String mid=input.nextLine();
String next=input.nextLine();
System.out.println(change(mid,next));
}
private static String change(String mid, String next) {
if(mid.length()>0){
int len=next.length();
if(len == 1)
return next;
if(len <= 0 ||len > 8)
return "";
char root=next.charAt(len - 1);
int rootIndex = mid.indexOf(root);
return next.charAt(len - 1) + change(mid.substring(0,rootIndex),next.substring(0,rootIndex)) + change(mid.substring(rootIndex+1),next.substring(rootIndex,len - 1));
}else
return "";
}