package.json

@@ -4,7 +4,7 @@
   "description": "Algorithms and data-structures implemented on JavaScript",
   "main": "index.js",
   "scripts": {
-    "lint": "eslint ./src/*",
+    "lint": "eslint . --ext .js --ignore-path .gitignore",
     "test": "jest",
     "ci": "npm run lint && npm run test -- --coverage"
   },

src/algorithms/math/binary/README.md

@@ -0,0 +1,40 @@
+# Conversion of Binary number to Decimal number
+Given a binary number as input, we need to write a program to convert the given binary number into equivalent decimal number.
+
+The idea is to extract the digits of given binary number starting from right most digit and keep a variable decimal_value. At the time of extracting digits from the binary number, multiply the digit with the proper base (Power of 2) and add it to the variable decimal_value. At the end, the variable decimal_value will store the required decimal number.
+
+For Example:
+If the binary number is 111.
+decimal_value = 1*(2^2) + 1*(2^1) + 1*(2^0) = 7
+
+![](images/binaryToDecimal.PNG)
+
+
+## Reference
+<a href="https://www.youtube.com/watch?v=meGcdIoTYgw">Youtube</a>
+
+# Conversion of Decimal number to Binary number
+Given a decimal number as input, we need to write a program to convert the given decimal number into equivalent binary number.
+
+
+  Store the remainder when the number is divided by 2 in an array.
+  Divide the number by 2
+  Repeat the above two steps until the number is greater than zero.
+  Print the array in reverse order now.
+
+For Example:
+If the binary number is 10.
+Step 1: Remainder when 10 is divided by 2 is zero. Therefore, arr[0] = 0.
+Step 2: Divide 10 by 2. New number is 10/2 = 5.
+Step 3: Remainder when 5 is divided by 2 is 1. Therefore, arr[1] = 1.
+Step 4: Divide 5 by 2. New number is 5/2 = 2.
+Step 5: Remainder when 2 is divided by 2 is zero. Therefore, arr[2] = 0.
+Step 6: Divide 2 by 2. New number is 2/2 = 1.
+Step 7: Remainder when 1 is divided by 2 is 1. Therefore, arr[3] = 1.
+Step 8: Divide 1 by 2. New number is 1/2 = 0.
+Step 9: Since number becomes = 0. Print the array in reverse order. Therefore the equivalent binary number is 1010.
+
+![](images/decimalToBinary.PNG)
+
+## Reference
+<a href="https://www.youtube.com/watch?v=mW8NIJ6Ns8k">Youtube</a>

src/algorithms/math/binary/__test__/binaryToDecimal.test.js

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+import binaryToDecimal from '../binaryToDecimal';
+
+describe('Convert a binary number to decimal number', () => {
+  it('should return decimal number', () => {
+    expect(binaryToDecimal(101)).toBe(5);
+    expect(binaryToDecimal(1101010101)).toBe(853);
+    expect(binaryToDecimal(22323)).toBe('Enter the valid number');
+  });
+});

src/algorithms/math/binary/__test__/decimalToBinary.test.js

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+import decimalToBinary from '../decimalToBinary';
+
+describe('Convert a decimal number to binary number', () => {
+  it('should return decimal number', () => {
+    expect(decimalToBinary(0)).toBe(0);
+    expect(decimalToBinary(1)).toBe(1);
+    expect(decimalToBinary(5)).toBe(101);
+    expect(decimalToBinary(10)).toBe(1010);
+    expect(decimalToBinary(853)).toBe(1101010101);
+    expect(decimalToBinary(1010)).toBe(1111110010);
+    expect(decimalToBinary(12345)).toBe(11000000111001);
+    expect(decimalToBinary('abc1230')).toBe('Enter a valid decimal number');
+  });
+});

src/algorithms/math/binary/binaryToDecimal.js

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+/**
+ * @param {number} binary number
+ * @return {number} decimal number
+ */
+// function to check if the number entered is binary
+function checkIfBinary(binaryString) {
+  for (let i = 0; i < binaryString.length; i += 1) {
+    if (binaryString[i] > 1) {
+      return false;
+    }
+  }
+  return true;
+}
+
+export default function binaryToDecimal(binaryNumber) {
+  const binaryString = binaryNumber.toString();
+  let decimalNumber = 0;
+  // checks if the number entered is binary
+  const checkForBinary = checkIfBinary(binaryString);
+  if (binaryString.length !== 0 && checkForBinary === true) {
+    for (let i = 0; i < binaryString.length; i += 1) {
+      decimalNumber += binaryString[binaryString.length - 1 - i] * (2 ** i);
+    }
+  } else {
+    return 'Enter the valid number';
+  }
+  return decimalNumber;
+}

src/algorithms/math/binary/decimalToBinary.js

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+/**
+ * @param {number} decimal number
+ * @return {number} binary number
+ */
+// to check if the entered number is a decimal number
+function checkIfDecimal(decimalNumber) {
+  return !Number.isNaN(parseInt(decimalNumber, 10));
+}
+
+export default function decimalToBinary(decimalNumbers) {
+  const binaryNumber = [];
+  let decimalNumber = decimalNumbers;
+  const checkForDecimal = checkIfDecimal(decimalNumber);
+  if (checkForDecimal) {
+    while (decimalNumber > -1) {
+      if (decimalNumber > 1) {
+        binaryNumber.push(decimalNumber % 2);
+        decimalNumber = parseInt(decimalNumber / 2, 10);
+      } else {
+        binaryNumber.push(decimalNumber);
+        break;
+      }
+    }
+  } else {
+    return 'Enter a valid decimal number';
+  }
+  return parseInt(binaryNumber.reverse().join(''), 10);
+}