Java memoized code gives StackOverFlow error at Runtime

[sarvjeet-singh_661]

bottom up solution works fine ,
but top-down memoized code(JAVA) shows STACKOVERFLOW error,
“Exception in thread “main” java.lang.StackOverflowError”.

Here is my code

public class Solution {
// DO NOT MODIFY THE LIST. IT IS READ ONLY

class pair
{
    int min;
    int max;
    pair(int a,int b)
    {
        this.min=a;
        this.max=b;
    }
}
public pair find(pair dp[],List<Integer> al,int e)
{
    if(e==0)
    {
        dp[0]=new pair(al.get(0),al.get(0));
        return (dp[0]);
    }
    if(dp[e]!=null) return dp[e];
    
    pair p1=find(dp,al,e-1);
    int a=al.get(e)*p1.max;
    int b=al.get(e)*p1.min;
    int c=al.get(e);
    
    int t1=Math.max(a,Math.max(b,c));
    int t2=Math.min(a,Math.min(b,c));
    
   
  dp[e]=new pair(t2,t1);
    return dp[e];
    
}

public int maxProduct(final List<Integer> al) {
    
   pair dp[]=new pair[al.size()];
   pair t1= find(dp,al,al.size()-1);
   
   //System.out.println(t1.max);
   int mm=Integer.MIN_VALUE;
   for(int i=0;i<dp.length;i++)
   {
      //System.out.println(dp[i].max);
       mm=Math.max(mm,dp[i].max);
       
   }
   return mm;
    
}

}