From 7af96ae1cc33e48b7e692e854ec9da1ff4635f23 Mon Sep 17 00:00:00 2001
From: AbhinavXT <abhinavpathaka17@gmail.com>
Date: Sun, 11 Jul 2021 16:30:23 +0530
Subject: [PATCH] Added HammingDistance.js and HammingDistance.test.js in
 String directory

---
 String/HammingDistance.js           | 32 +++++++++++++++++++++++++++++
 String/test/HammingDistance.test.js | 21 +++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 String/HammingDistance.js
 create mode 100644 String/test/HammingDistance.test.js

diff --git a/String/HammingDistance.js b/String/HammingDistance.js
new file mode 100644
index 000000000..d3316f198
--- /dev/null
+++ b/String/HammingDistance.js
@@ -0,0 +1,32 @@
+/**
+ * Hamming Distance: https://en.wikipedia.org/wiki/Hamming_distance
+ *
+ *
+ * Hamming distance is a metric for comparing two binary data strings.
+ *
+ * While comparing two binary strings of equal length, Hamming distance
+ * is the number of bit positions in which the two bits are different.
+ * The Hamming distance between two strings, a and b is denoted as d(a,b)
+ */
+
+/**
+ * @param {string} a
+ * @param {string} b
+ * @return {number}
+ */
+
+export const hammingDistance = (a, b) => {
+  if (a.length !== b.length) {
+    throw new Error('Strings must be of the same length')
+  }
+
+  let distance = 0
+
+  for (let i = 0; i < a.length; i += 1) {
+    if (a[i] !== b[i]) {
+      distance += 1
+    }
+  }
+
+  return distance
+}
diff --git a/String/test/HammingDistance.test.js b/String/test/HammingDistance.test.js
new file mode 100644
index 000000000..bc52cafc6
--- /dev/null
+++ b/String/test/HammingDistance.test.js
@@ -0,0 +1,21 @@
+import { hammingDistance } from '../HammingDistance'
+
+test('should throw an error when trying to compare the strings of different length', () => {
+  const compareStringsOfDifferentLength = () => {
+    hammingDistance('abc', 'abcd')
+  }
+
+  expect(compareStringsOfDifferentLength).toThrowError()
+})
+
+test('should calculate difference between two strings', () => {
+  expect(hammingDistance('a', 'a')).toBe(0)
+})
+
+test('should calculate difference between two strings', () => {
+  expect(hammingDistance('abc', 'add')).toBe(2)
+})
+
+test('should calculate difference between two strings', () => {
+  expect(hammingDistance('1011101', '1001001')).toBe(2)
+})