Php Program for Products of ranges in an array

Given an array A[] of size N. Solve Q queries. Find the product in the range [L, R] under modulo P ( P is Prime). 

Examples:

Input : A[] = {1, 2, 3, 4, 5, 6} 
          L = 2, R = 5, P = 229
Output : 120

Input : A[] = {1, 2, 3, 4, 5, 6},
         L = 2, R = 5, P = 113
Output : 7 

Brute Force
For each of the queries, traverse each element in the range [L, R] and calculate the product under modulo P. This will answer each query in O(N).  

PHP

<?php
// Product in range Queries in O(N)

// Function to calculate
// Product in the given range.
function calculateProduct($A, $L,
                          $R, $P)
{
    // As our array is 0 based as
    // and L and R are given as 1
    // based index.
    $L = $L - 1;
    $R = $R - 1;

    $ans = 1;
    for ($i = $L; $i <= $R; $i++)
    {
        $ans = $ans * $A[$i];
        $ans = $ans % $P;
    }

    return $ans;
}

// Driver code
$A = array( 1, 2, 3, 4, 5, 6 );
$P = 229;
$L = 2; $R = 5;
echo calculateProduct($A, $L, $R, $P),"
" ;

$L = 1; $R = 3;
echo calculateProduct($A, $L, $R, $P),"
" ;

// This code is contributed by ajit.
?>

Output :

120
6

Please refer complete article on Products of ranges in an array for more details!