TADM2E 3.28

We need two passes over X:

1. Calculate cumulative production P and Q:
$ P_0 = 1, P_k=X_k P_{k-1}=\prod_{i=1}^kx_i $
$ Q_n = 1, Q_k=X_k Q_{k+1}=\prod_{i=k}^nx_i $

2. Calculate M:
$ M_k=P_{k-1}Q_{k+1}, k\in[1,n] $

---

Using Iteration

public class Multiplication {
	
       private static int productLeft(int[] x,int i,int j){
		if(i<0)
			return 1;
		return x[i]*productLeft(x, i-1, j);
	}
       private static int productRight(int[] x,int i,int j){
		if(i>=j)
			return 1;
		return x[i]*productRight(x, i+1, j);
	}
        private static int product(int[] x,int[] y,int i,int j){	
	   if(i==j){
		   return productLeft(x, i-2, j);
        }
	return x[i]*productLeft(x, i-2, j)*productRight(x, i+1, j);
            }
   public static int[] product(int[] x){	   
	   int[] M=new int[x.length];
	   for (int i=0;i<x.length;i++){
		    M[i]=product(x, M, i+1, x.length); 
	   }
	   return M;
   }
}

--Tnoumessi (talk) 00:21, 8 April 2015 (EDT)