Adding PHP Implementation for Chinese Rem. Th. (jainaman224#2685)

Chinese_Remainder_Theorem/Chinese_Remainder_Theorem.php

@@ -0,0 +1,57 @@
+<?php 
+// Implementation of Chinese Remainder Theorem in PHP
+
+// function to find modular multiplicative inverse of 
+// 'val' under modulo 'm' 
+function modInv($val, $m) { 
+    $val = $val % $m; 
+    for ($x = 1; $x < $m; $x++) 
+        if (($val * $x) % $m == 1) 
+            return $x; 
+} 
+
+/* 
+findVal() returns the smallest number reqValue such that: 
+reqValue % div[0] = rem[0], 
+reqValue % div[1] = rem[1], 
+..... 
+reqValue % div[k-2] = rem[k-1] 
+It is assumed that the numbers in div[] are pairwise coprime. 
+*/
+function findVal($div, $rem, $size) { 
+	// $totalProd represents product of all numbers 
+	$totalProd = 1; 
+	for ($i = 0; $i < $size; $i++) 
+		$totalProd *= $div[$i]; 
+
+    // $result represents summation of 
+    // (rem[i] * partialProd[i] * modInv[i]) 
+    // for 0 <= i <= size-1
+	$result = 0; 
+	for ($i = 0; $i < $size; $i++) { 
+		$partialProd = (int)$totalProd / $div[$i]; 
+		$result += $rem[$i] * $partialProd * modInv($partialProd, $div[$i]); 
+	} 
+
+    $reqValue = $result % $totalProd;
+    return $reqValue; 
+} 
+
+// Sample case to test the code
+$divisor = array(5, 7, 8); 
+$remainder = array(3, 1, 6); 
+$size = sizeof($divisor); 
+echo "Value is ". findVal($divisor, $remainder, $size); 
+
+
+/* 
+Sample Input as specified in the code:
+Divisors: 5, 7, 8
+Remainders: 3, 1, 6
+
+Sample Output:
+Value is 78
+*/
+
+?> 
+