Add bitsDiff function.

Author: trekhleb

src/algorithms/math/bits/README.md

@@ -91,20 +91,6 @@ inverting all of the bits of the number and adding 1 to it.
 
 > See `switchSign` function for further details.
 
-#### Count Bits to Flip One Number to Another
-
-This methods outputs the number of bits required to convert a number to another. This
-makes use of property that when numbers are XORed the result will be number of different
-bits and `countSetBits`.
-
-``
-Number A : 5 = (0101)_2
-Number B : 1 = (0001)_2
-Count Bits to be Flipped: 1
-``
-
-> See `countBitsToflipAToB` function for further details.
-
 #### Multiply Two Numbers
 
 This method multiplies two integer numbers using bitwise operators.
@@ -143,6 +129,19 @@ Count of set bits = 2
 
 > See `countSetBits` function for further details.
 
+#### Count Bits to Flip One Number to Another
+
+This methods outputs the number of bits required to convert one number to another.
+This makes use of property that when numbers are `XOR`-ed the result will be number
+of different bits.
+
+```
+5 = 0b0101
+1 = 0b0001
+Count of Bits to be Flipped: 1
+```
+
+> See `bitsDiff` function for further details.
 
 ## References
 

src/algorithms/math/bits/__test__/bitsDiff.test.js

@@ -0,0 +1,13 @@
+import bitsDiff from '../bitsDiff';
+
+describe('bitsDiff', () => {
+  it('should calculate bits difference between two numbers', () => {
+    expect(bitsDiff(0, 0)).toBe(0);
+    expect(bitsDiff(1, 1)).toBe(0);
+    expect(bitsDiff(124, 124)).toBe(0);
+    expect(bitsDiff(0, 1)).toBe(1);
+    expect(bitsDiff(1, 0)).toBe(1);
+    expect(bitsDiff(1, 2)).toBe(2);
+    expect(bitsDiff(1, 3)).toBe(1);
+  });
+});

src/algorithms/math/bits/bitsDiff.js

@@ -0,0 +1,13 @@
+import countSetBits from './countSetBits';
+
+/**
+ * Counts the number of bits that need to be change in order
+ * to convert numberA to numberB.
+ *
+ * @param {number} numberA
+ * @param {number} numberB
+ * @return {number}
+ */
+export default function bitsDiff(numberA, numberB) {
+  return countSetBits(numberA ^ numberB);
+}