[pull] master from TheAlgorithms:master

Backtracking/GeneratePermutations.js

@@ -1,5 +1,5 @@
 /*
- * Problem Statement: Generate all distinct permutations of a an array (all permutations should be in sorted order);
+ * Problem Statement: Generate all distinct permutations of an array (all permutations should be in sorted order);
  *
  * What is permutations?
  * - Permutation means possible arrangements in a set (here it is an array);

Bit-Manipulation/GrayCodes.js

@@ -0,0 +1,42 @@
+/**
+ * Generates a Gray code sequence for the given number of bits.
+ * @param {number} n - The number of bits in the Gray code sequence.
+ * @returns {number[]} - An array of Gray codes in binary format.
+ * @description
+ * Gray codes are binary sequences in which two successive values differ in only one bit.
+ * This function generates a Gray code sequence of length 2^n for the given number of bits.
+ *
+ * The algorithm follows these steps:
+ *
+ * 1. Initialize an array `grayCodes` to store the Gray codes. Start with [0, 1] for n = 1.
+ * 2. Iterate from 1 to n:
+ *    a. Calculate `highestBit` as 2^i, where `i` is the current iteration index.
+ *    b. Iterate in reverse order through the existing Gray codes:
+ *       - For each Gray code `code`, add `highestBit | code` to `grayCodes`.
+ *       - This operation flips a single bit in each existing code, creating new codes.
+ * 3. Return the `grayCodes` array containing the Gray codes in decimal representation.
+ *
+ *resources: [GFG](https://www.geeksforgeeks.org/generate-n-bit-gray-codes/)
+ * @example
+ * const n = 3;
+ * const grayCodes = generateGrayCodes(n);
+ * // grayCodes will be [0, 1, 3, 2, 6, 7, 5, 4] for n=3.
+ */
+function generateGrayCodes(n) {
+  if (n <= 0) {
+    return [0]
+  }
+
+  const grayCodes = [0, 1]
+
+  for (let i = 1; i < n; i++) {
+    const highestBit = 1 << i
+    for (let j = grayCodes.length - 1; j >= 0; j--) {
+      grayCodes.push(highestBit | grayCodes[j])
+    }
+  }
+
+  return grayCodes
+}
+
+export { generateGrayCodes }

Bit-Manipulation/test/GrayCodes.test.js

@@ -0,0 +1,19 @@
+import { generateGrayCodes } from '../GrayCodes.js'
+
+describe('Gray codes', () => {
+  test.each([
+    [0, [0b0]],
+    [1, [0b0, 0b1]],
+    [2, [0b00, 0b01, 0b11, 0b10]],
+    [3, [0b000, 0b001, 0b011, 0b010, 0b110, 0b111, 0b101, 0b100]],
+    [
+      4,
+      [
+        0b0000, 0b0001, 0b0011, 0b0010, 0b0110, 0b0111, 0b0101, 0b0100, 0b1100,
+        0b1101, 0b1111, 0b1110, 0b1010, 0b1011, 0b1001, 0b1000
+      ]
+    ]
+  ])('n = %i -> %j', (n, expected) => {
+    expect(generateGrayCodes(n)).toEqual(expected)
+  })
+})

Ciphers/KeyFinder.js

@@ -1,7 +1,8 @@
-/******************************************************
- Find and retrieve the encryption key automatically
- Note: This is a draft version, please help to modify, Thanks!
- ******************************************************/
+/**
+ * Find and retrieve the encryption key automatically.
+ * @param {string} str - The input encrypted string.
+ * @returns {number} - The encryption key found, or 0 if not found.
+ */
 function keyFinder(str) {
   // str is used to get the input of encrypted string
   const wordBank = [
@@ -30,8 +31,6 @@ function keyFinder(str) {
     ' be ',
     'Be '
   ]
-  // let wordbankelementCounter = 0;
-  // let key = 0; // return zero means the key can not be found
   const inStr = str.toString() // convert the input to String
   let outStr = '' // store the output value
   let outStrElement = '' // temporary store the word inside the outStr, it is used for comparison
@@ -59,89 +58,95 @@ function keyFinder(str) {
   return 0 // return 0 if found nothing
 }
 
-/* this sub-function is used to assist the keyFinder to find the key */
+/**
+ * This sub-function is used to assist the keyFinder in finding the key.
+ * @param {string} inStr - The input string.
+ * @param {number} numShifted - The number of characters to shift in the Caesar cipher.
+ * @returns {string} - The decrypted string.
+ */
 function caesarCipherEncodeAndDecodeEngine(inStr, numShifted) {
   const shiftNum = numShifted
   let charCode = 0
-  let outStr = ''
   let shiftedCharCode = 0
   let result = 0
 
-  for (let i = 0; i < inStr.length; i++) {
-    charCode = inStr[i].charCodeAt()
-    shiftedCharCode = charCode + shiftNum
-    result = charCode
+  return inStr
+    .split('')
+    .map((char) => {
+      charCode = char.charCodeAt()
+      shiftedCharCode = charCode + shiftNum
+      result = charCode
 
-    if (charCode >= 48 && charCode <= 57) {
-      if (shiftedCharCode < 48) {
-        let diff = Math.abs(48 - 1 - shiftedCharCode) % 10
+      if (charCode >= 48 && charCode <= 57) {
+        if (shiftedCharCode < 48) {
+          let diff = Math.abs(48 - 1 - shiftedCharCode) % 10
 
-        while (diff >= 10) {
-          diff = diff % 10
-        }
-        document.getElementById('diffID').innerHTML = diff
+          while (diff >= 10) {
+            diff = diff % 10
+          }
+          document.getElementById('diffID').innerHTML = diff
 
-        shiftedCharCode = 57 - diff
+          shiftedCharCode = 57 - diff
 
-        result = shiftedCharCode
-      } else if (shiftedCharCode >= 48 && shiftedCharCode <= 57) {
-        result = shiftedCharCode
-      } else if (shiftedCharCode > 57) {
-        let diff = Math.abs(57 + 1 - shiftedCharCode) % 10
+          result = shiftedCharCode
+        } else if (shiftedCharCode >= 48 && shiftedCharCode <= 57) {
+          result = shiftedCharCode
+        } else if (shiftedCharCode > 57) {
+          let diff = Math.abs(57 + 1 - shiftedCharCode) % 10
 
-        while (diff >= 10) {
-          diff = diff % 10
-        }
-        document.getElementById('diffID').innerHTML = diff
+          while (diff >= 10) {
+            diff = diff % 10
+          }
+          document.getElementById('diffID').innerHTML = diff
 
-        shiftedCharCode = 48 + diff
+          shiftedCharCode = 48 + diff
 
-        result = shiftedCharCode
-      }
-    } else if (charCode >= 65 && charCode <= 90) {
-      if (shiftedCharCode <= 64) {
-        let diff = Math.abs(65 - 1 - shiftedCharCode) % 26
-
-        while (diff % 26 >= 26) {
-          diff = diff % 26
+          result = shiftedCharCode
         }
-        shiftedCharCode = 90 - diff
-        result = shiftedCharCode
-      } else if (shiftedCharCode >= 65 && shiftedCharCode <= 90) {
-        result = shiftedCharCode
-      } else if (shiftedCharCode > 90) {
-        let diff = Math.abs(shiftedCharCode - 1 - 90) % 26
-
-        while (diff % 26 >= 26) {
-          diff = diff % 26
+      } else if (charCode >= 65 && charCode <= 90) {
+        if (shiftedCharCode <= 64) {
+          let diff = Math.abs(65 - 1 - shiftedCharCode) % 26
+
+          while (diff % 26 >= 26) {
+            diff = diff % 26
+          }
+          shiftedCharCode = 90 - diff
+          result = shiftedCharCode
+        } else if (shiftedCharCode >= 65 && shiftedCharCode <= 90) {
+          result = shiftedCharCode
+        } else if (shiftedCharCode > 90) {
+          let diff = Math.abs(shiftedCharCode - 1 - 90) % 26
+
+          while (diff % 26 >= 26) {
+            diff = diff % 26
+          }
+          shiftedCharCode = 65 + diff
+          result = shiftedCharCode
         }
-        shiftedCharCode = 65 + diff
-        result = shiftedCharCode
-      }
-    } else if (charCode >= 97 && charCode <= 122) {
-      if (shiftedCharCode <= 96) {
-        let diff = Math.abs(97 - 1 - shiftedCharCode) % 26
-
-        while (diff % 26 >= 26) {
-          diff = diff % 26
-        }
-        shiftedCharCode = 122 - diff
-        result = shiftedCharCode
-      } else if (shiftedCharCode >= 97 && shiftedCharCode <= 122) {
-        result = shiftedCharCode
-      } else if (shiftedCharCode > 122) {
-        let diff = Math.abs(shiftedCharCode - 1 - 122) % 26
-
-        while (diff % 26 >= 26) {
-          diff = diff % 26
+      } else if (charCode >= 97 && charCode <= 122) {
+        if (shiftedCharCode <= 96) {
+          let diff = Math.abs(97 - 1 - shiftedCharCode) % 26
+
+          while (diff % 26 >= 26) {
+            diff = diff % 26
+          }
+          shiftedCharCode = 122 - diff
+          result = shiftedCharCode
+        } else if (shiftedCharCode >= 97 && shiftedCharCode <= 122) {
+          result = shiftedCharCode
+        } else if (shiftedCharCode > 122) {
+          let diff = Math.abs(shiftedCharCode - 1 - 122) % 26
+
+          while (diff % 26 >= 26) {
+            diff = diff % 26
+          }
+          shiftedCharCode = 97 + diff
+          result = shiftedCharCode
         }
-        shiftedCharCode = 97 + diff
-        result = shiftedCharCode
       }
-    }
-    outStr = outStr + String.fromCharCode(parseInt(result))
-  }
-  return outStr
+      return String.fromCharCode(parseInt(result))
+    })
+    .join('')
 }
 
 export { keyFinder }

DIRECTORY.md

@@ -179,6 +179,7 @@
   * [DecimalExpansion](Maths/DecimalExpansion.js)
   * [DecimalIsolate](Maths/DecimalIsolate.js)
   * [DegreeToRadian](Maths/DegreeToRadian.js)
+  * [EuclideanDistance](Maths/EuclideanDistance.js)
   * [EulerMethod](Maths/EulerMethod.js)
   * [EulersTotient](Maths/EulersTotient.js)
   * [EulersTotientFunction](Maths/EulersTotientFunction.js)
@@ -249,6 +250,7 @@
   * [SumOfDigits](Maths/SumOfDigits.js)
   * [SumOfGeometricProgression](Maths/SumOfGeometricProgression.js)
   * [TwinPrime](Maths/TwinPrime.js)
+  * [TwoSum](Maths/TwoSum.js)
   * [Volume](Maths/Volume.js)
   * [WhileLoopFactorial](Maths/WhileLoopFactorial.js)
   * [ZellersCongruenceAlgorithm](Maths/ZellersCongruenceAlgorithm.js)