algorithm: Added Hamming Distance

DIRECTORY.md

@@ -20,6 +20,7 @@
   * [Fibonacci](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/fibonacci.ts)
   * [Find Min](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/find_min.ts)
   * [Greatest Common Factor](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/greatest_common_factor.ts)
+  * [Hamming Distance](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/hamming_distance.ts)
   * [Is Divisible](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_divisible.ts)
   * [Is Even](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_even.ts)
   * [Is Leap Year](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_leap_year.ts)

maths/hamming_distance.ts

@@ -0,0 +1,25 @@
+/**
+ * @function HammingDistance
+ * @description Returns the Hamming distance between two strings of equal length
+ * @summary The Hamming distance between two strings of equal length is the
+ * number of positions at which the corresponding symbols are different. In other words,
+ * it measures the minimum number of substitutions required, to change one string to the other
+ * It is one of the several sring metrics, used fror measuring the edit distance between two sequences
+ * and is named after the American mathematician Richard Hamming
+ * @param str1 One of the strings to compare to the other
+ * @param str2 One of the strings to compare to the other
+ * @returns {number}
+ * @see [Wikipedia](https://en.wikipedia.org/wiki/Hamming_distance)
+ * @example HammingDistance('happy', 'homie')
+ */
+const HammingDistance = (str1: string, str2: string) => {
+  if (str1.length !== str2.length) throw new Error('Strings must of the same length.')
+
+  let dist = 0
+
+  for (let i = 0; i < str1.length; i++) if (str1[i] !== str2[i]) dist++
+
+  return dist
+}
+
+export { HammingDistance }

maths/test/hamming_distance.test.ts

@@ -0,0 +1,5 @@
+import { HammingDistance } from "../hamming_distance"
+
+test.each([['happy', 'homie', 4], ['hole', 'home', 1], ['cathrine', 'caroline', 3], ['happiness', 'dizziness', 4]])('Hamming Distance', (str1, str2, result) => {
+  expect(HammingDistance(str1, str2)).toBe(result)
+})