Added a short explanation of the Ext Euc Algo

Author: VinWare

Maths/ExtendedEuclideanGCD.js

@@ -2,8 +2,20 @@
  * Problem statement and explanation: https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
  *
  * This algorithm plays an important role for modular arithmetic, and by extension for cyptography algorithms
- *
- * This implementation uses an iterative approach to calculate
+ * 
+ * Basic explanation:
+ * The Extended Euclidean algorithm is a modification of the standard Euclidean GCD algorithm.
+ * It allows to calculate coefficients x and y for the equation:
+ *          ax + by = gcd(a,b)
+ * 
+ * This is called Bézout's identity and the coefficients are called Bézout coefficients
+ * 
+ * The algorithm uses the Euclidean method of getting remainder:
+ * r_i+1 = r_i-1 - qi*ri
+ * and applies it to series s and t (with same quotient q at each stage)
+ * When r_n reaches 0, the value r_n-1 gives the gcd, and s_n-1 and t_n-1 give the coefficients
+ * 
+ * This implementation uses an iterative approach to calculate the values
  */
 
 /**
@@ -57,4 +69,3 @@ const extendedEuclideanGCD = (arg1, arg2) => {
 }
 
 export { extendedEuclideanGCD }
-// ex