Recursion:returning the largest value in a linked list

Question

import java.io.*;
import java.util.*;
class Node{
     int num;
     Node next;
     Node(int n){
          num = n;
          next = null;
class RecursivePrint{
     public static void main(String[] args){
          Node np, last;
          Node top = null;
          last = null;
          for(int i = 1; i <11; i++){
               np = new Node(i);
               if(top==null)top = np;
                    else
               last.next = np;
               last = np;
          int x =Largest(top);
         System.out.println("large is "+ x);
     }//end main
     public static int Largest(Node top){
          int large = 0;
          if(top==null){
               return 0;
               while(top!=null){
           if(top.num > large){
               large = top.num;
               //top = top.next;
          Largest(top.next);     
     }//while
     return large;
}//end class
I am trying to return the largest value in a linked list (10) in this case.  when I do it withour recurrsion it works ok, but when I try it with recurrsion it dies.  The logic seems ok to me, cannot figure why it dies.

Answer 1

chetah wrote:
public static int Largest(Node top){
          int large = 0;
          if(top==null){
               return 0;
          if(top.num > large){
               large = top.num;
               //top = top.next;
               Largest(top.next);
     return large;
Initially I had the above, it return only 1 that was the reason for puting the loop.You don't seem to understand recursion or variable scope.
int large = 0;large is a different variable inside each instance of the method.
So when you get back up to the value 1 from the recursive calls its just comparing 1 to 0
Here's a solution...
     public static int Largest(Node top){
          if(top.next != null){
               if(Largest(top.next) > top.num)
                    return Largest(top.next);}
          return top.num;
     }