Added more implementations (JS) (#67)

* Added recursive binary search (JS)

* Added recursive selection sorting

* Added another loop implementation sum func by reduce (JS)

* Recursion reduced by one iteration

* Recursive binary search in ES6 added to appropriate folder

* JS files ordered by standards (ES4/ES6)

* Added hashtable implementation in JS

* Fixed typo with LENGTH prop

* Added Euclidian algorithm for two numbers and set of them

* Added universal selection sort

* Commented output

* Added ES6 version of Euclidean algorithm

* Converted from ES6 to ES5

* #69 Added search for LCS

* #69 added levenstein algorithm

* Removed excessive property

* Removed excessive file

* Removed excessive function calls

* Removed excessive file

* Removed excessive file

* Renamed

* Fixed indentation

01_introduction_to_algorithms/ES6/02_recursive_binary_search.js

@@ -0,0 +1,43 @@
+/**
+ * Searches recursively number from the list
+ * @param {Array} list
+ * @param {number} item Search item
+ * @param {number} low Lower limit of search in the list
+ * @param {number} high Highest limit of search in the list
+ * @return {(number | null)} Number if the value is found or NULL otherwise
+ */
+const binarySearch = ( list, item, low, high ) => {
+    let arrLength = list.length;
+    while ( low <= high ) {
+        let mid = Math.floor((low + high) / 2);
+        let guess = list[mid];
+
+        if ( guess === item ) {
+            return mid;
+        } else if ( guess > item ) {
+            high = mid - 1;
+            list = list.slice( 0, mid );
+            return binarySearch( list, item, low, high );
+        } else {
+            low = mid + 1;
+            list = list.slice( low, arrLength );
+            return binarySearch( list, item, low, high );
+        }
+    }
+
+    return null;
+};
+
+/**
+ * Creates the array that contains numbers 1...N
+ * @param {number} n - number N
+ * @return {Array}
+ */
+const createArr = ( n ) => Array.from({length: n}, (v, k) => k + 1);
+
+const myList = createArr( 100 );
+let low = 0;
+let high = myList.length - 1;
+
+console.log( binarySearch( myList, 3, low, high ) ); // 2
+console.log( binarySearch( myList, -1, low, high ) ); // null

02_selection_sort/javascript/02_recursive_selection_sort.js

@@ -0,0 +1,33 @@
+/**
+ * Finds smallest element of an aray
+ * @param {Array} arr array for searching
+ * @return {number} index of the smallest element in array
+ */
+const findSmallest = ( arr ) => {
+    let smallest = arr[0];
+    let smallestIndex = 0;
+    let arrLen = arr.length;
+
+    for ( let i = 0; i < arrLen; i++ ) {
+        if ( arr[i] < smallest ) {
+            smallest = arr[i];
+            smallestIndex = i;
+        }
+    }
+    return smallestIndex;
+};
+
+/**
+ * Sorts0 recursively an array of numbers
+ * @param {Array} arr An array of numbers
+ * @return {Array} New sorted array
+ */
+const selectionSort = ( arr ) => {
+    if ( !arr.length ) return [];
+    let smallest = arr.splice( findSmallest( arr ), 1 );
+    return smallest.concat( selectionSort( arr ) );
+};
+
+let arr = [5, 3, 6, 2, 10];
+
+console.log( selectionSort(arr) );

04_quicksort/ES6/01_loop_sum.js

@@ -1,9 +1,18 @@
-const sum = (arr) => {
-  let total = 0;
-  for (let x = 0; x < arr.length; x += 1) {
-    total += arr[x];
-  }
-  return total;
+/**
+ * Sums values in array by loop "for"
+ * @param {Array} arr Array of numbers
+ * @return {number} Sum of the numbers
+ */
+const sumLoop = ( arr ) => {
+    let result = 0;
+
+    for ( let i = 0; i < newArr.length; i++ ) {
+        result += newArr[i];
+    }
+
+    return result;
 };
 
-console.log(sum([1, 2, 3, 4])); // 10
+let arr = [1, 2, 3, 4];
+
+console.log( sumLoop( arr ) ); // 10

04_quicksort/ES6/01_loop_sum_reduce_version.js

@@ -0,0 +1,16 @@
+/**
+ * Sums values in array by function "reduce"
+ * @param {Array} arr Array of numbers
+ * @return {number} Sum of the numbers
+ */
+const sumReduce = ( arr ) => {
+    let result = newArr.reduce( ( curr, prev ) => {
+        return curr + prev;
+    } );
+
+    return result;
+};
+
+let arr = [1, 2, 3, 4];
+
+console.log( sumReduce( arr ) ); // 10

04_quicksort/ES6/06_euclidean_algorithm_set_numbers.js

@@ -0,0 +1,36 @@
+/**
+ * Recursive function of Euclidean algorithm for two numbers
+ *
+ * @param {number} a first number
+ * @param {number} b second number (base case)
+ *
+ * @return {number} GCD (greatest common divisor)
+ */
+let gcdOfTwo = ( a, b ) => {
+    if ( !b ) {
+        return a;
+    }
+    return gcdOfTwo( b, a % b );
+};
+
+/**
+ * Recursive function of Euclidean algorithm for set of the numbers
+ *
+ * @param {Array} set Set of the numbers
+ *
+ * @return {number} GCD (greatest common divisor)
+ */
+let gcdOfSet = ( set ) => {
+    let result = set[0];
+    let newArr = Array.prototype.slice.call( set, 1 );
+
+    newArr.map( ( el ) => {
+        result = gcdOfTwo( result, el );
+    } );
+
+    return result;
+};
+
+const set = [1680, 640, 3360, 160, 240, 168000];
+
+console.log( gcdOfSet( set ) ); // 80

04_quicksort/ES6/07_euclidean_algorithm_two_numbers.js

@@ -0,0 +1,19 @@
+/**
+ * Recursive function of Euclidean algorithm
+ *
+ * @param {number} a first number
+ * @param {number} b second number (base case)
+ *
+ * @return {number} GCD (greatest common divisor)
+ */
+let getGCD = ( a, b ) => {
+    if ( !b ) {
+        return a;
+    }
+    return getGCD( b, a % b );
+};
+
+const a = 1680;
+const b = 640;
+
+console.log( getGCD( a, b ) ); // 80

04_quicksort/javascript/01_loop_sum.js

@@ -1,11 +1,18 @@
-'use strict';
+/**
+ * Sums values in array by loop "for"
+ * @param {Array} arr Array of numbers
+ * @return {number} Sum of the numbers
+ */
+function sumLoop( arr ) {
+    var result = 0;
 
-function sum(arr) {
-  let total = 0;
-  for (let x = 0; x < arr.length; x++) {
-    total += arr[x];
-  }
-  return total;
+    for ( var i = 0; i < newArr.length; i++ ) {
+        result += newArr[i];
+    }
+
+    return result;
 }
 
-console.log(sum([1, 2, 3, 4])) // 10
+var arr = [1, 2, 3, 4];
+
+console.log( sumLoop( arr ) ); // 10

04_quicksort/javascript/01_loop_sum_reduce_version.js

@@ -0,0 +1,16 @@
+/**
+ * Sums values in array by function "reduce"
+ * @param {Array} arr Array of numbers
+ * @return {number} Sum of the numbers
+ */
+function sumReduce( arr ) {
+    var result = newArr.reduce( ( curr, prev ) => {
+        return curr + prev;
+    } );
+
+    return result;
+}
+
+var arr = [1, 2, 3, 4];
+
+console.log( sumReduce( arr ) ); // 10

04_quicksort/javascript/02_recursive_sum.js

@@ -1,10 +1,13 @@
-'use strict';
+const arr = [1, 2, 3, 4];
 
-function sum(list) {
-  if (list.length === 0) {
-    return 0;
-  }
-  return list[0] + sum(list.slice(1));
-}
+/**
+ * Sums values in array recursively
+ * @param {Array} arr Array of numbers
+ * @return {number} Sum of the numbers
+ */
+const sumRecursive = ( arr ) => {
+    if ( arr.length == 1 ) return arr[0];
+    return arr[0] + sumRecursive( arr.slice( 1 ) );
+};
 
-console.log(sum([1, 2, 3, 4])) // 10
+console.log( sumRecursive( arr ) );  // 10

05_hash_tables/javascript/03_hashtable.js

@@ -0,0 +1,173 @@
+/**
+ * Class HashTable
+ *
+ * @param {object} obj
+ */
+let HashTable = function( obj ) {
+    let length = 0;
+    this._items = ( function( obj ) {
+        let items = {};
+        for ( let p in obj ) {
+                items[p] = obj[p];
+                length++;
+        }
+        return items;
+    }( obj ) );
+
+    /**
+     * Associates the specified value to the specified key
+     *
+     * @param {string} key The key to which associate the value
+     * @param {string} value The value to associate to the key
+     *
+     * @return {(undefined|object)} Undefined is object didn't exists before this call
+     */
+    this.set = function( key, value ) {
+        let previous = undefined;
+
+        if ( this.has( key ) ) {
+            previous = this._items[key];
+        } else {
+            length++;
+        }
+
+        this._items[key] = value;
+
+        return previous;
+    };
+
+    /**
+     * Returns the value associated to the specified key
+     *
+     * @param {string} key The key from which retrieve the value
+     *
+     * @return {(undefined|string)} Undefined or associated value
+     */
+    this.get = function( key ) {
+        return this._items.hasOwnProperty( key ) ? this._items[key] : undefined;
+    };
+
+    /**
+     * Returns whether the hashtable contains the specified key
+     *
+     * @param {string} key The key to check
+     *
+     * @return {boolean}
+     */
+    this.has = function( key ) {
+        return this._items.hasOwnProperty( key );
+    };
+
+    /**
+     * Removes the specified key with its value
+     *
+     * @param {string} key The key to remove
+     *
+     * @return {(undefined|string)} Undefined if key doesn't exist and
+     * string (previous value) - value of deleted item
+     */
+    this.remove = function( key ) {
+        if ( this.has( key ) ) {
+            let previous = this._items[key];
+            length--;
+            delete this._items[key];
+            return previous;
+        } else {
+            return undefined;
+        }
+    };
+
+    /**
+     * Returns an array with all the registered keys
+     *
+     * @return {array}
+     */
+    this.getKeys = function() {
+        let keys = [];
+
+        for ( let i in this._items ) {
+            if ( this.has( i ) ) {
+                keys.push( i );
+            }
+        }
+
+        return keys;
+    };
+
+    /**
+     * Returns an array with all the registered values
+     *
+     * @return {array}
+     */
+    this.getValues = function() {
+        let values = [];
+
+        for ( let i in this._items ) {
+            if ( this.has( i ) ) {
+                values.push( this._items[i] );
+            }
+        }
+
+        return values;
+    };
+
+    /**
+     * Iterates all entries in the specified iterator callback
+     * @param {function} callback A method with 2 parameters: key, value
+     */
+    this.each = function( callback ) {
+        for ( let i in this._items ) {
+            if ( this.has( i ) ) {
+                callback( i, this._items[i] );
+            }
+        }
+    };
+
+    /**
+     * Deletes all the key-value pairs on the hashmap
+     */
+    this.clear = function() {
+        this._items = {};
+        length = 0;
+    };
+
+    /**
+     * Gets the count of the entries in the hashtable
+     */
+    Object.defineProperty( this, 'length', {
+        get: function() {
+            return length;
+        },
+    });
+
+    /**
+     * Gets an array of all keys in the hashtable
+     */
+    Object.defineProperty(this, 'keys', {
+        get: function() {
+            return this.getKeys();
+        },
+    });
+
+    /**
+     * Gets an array of all values in the hashtable
+     */
+    Object.defineProperty(this, 'values', {
+        get: function() {
+            return this.getValues();
+        },
+    });
+};
+
+let hashtable = new HashTable({'one': 1, 'two': 2, 'three': 3, 'cuatro': 4});
+
+console.log( 'Original length: ' + hashtable.length ); // Original length: 4
+console.log( 'Value of key "one": ' + hashtable.get( 'one' ) ); // Value of key "one": 1
+console.log( 'Has key "foo"? ' + hashtable.has( 'foo' )); // Has key "foo"? false
+console.log( 'Previous value of key "foo": ' + hashtable.set( 'foo', 'bar' ) ); // Previous value of key "foo": undefined
+console.log( 'Length after set: ' + hashtable.length ); // Length after set: 5
+console.log( 'Value of key "foo": ' + hashtable.get( 'foo' ) ); // Value of key "foo": bar
+console.log( 'Value of key "cuatro": ' + hashtable.get( 'cuatro' )); // Value of key "cuatro": 4
+console.log( 'Get keys by using property: ' + hashtable.keys ); // Get keys by using property: one,two,three,cuatro,foo
+hashtable.clear();
+console.log( 'Length after clear: ' + hashtable.length ); // Length after clear: 0

09_dynamic_programming/javascript/01_longest_common_subsequence.js

@@ -1,7 +1,78 @@
-if (word_a[i] === word_b[j]) {
-  // The letters match
-  cell[i][j] = cell[i-1][j-1] + 1;
-} else {
-  // The letters don't match
-  cell[i][j] = Math.max(cell[i-1][j], cell[i][j-1]);
+/**
+ * Search for LCS
+ *
+ * @param {string} string1 first string
+ * @param {string} string2 second string
+ *
+ * @return {object} with keys: lcs, offset, sequence
+ */
+function lcs(string1, string2) {
+	if (!string1 || !string2) {
+		return {
+			lcs: 0,
+			offset: 0,
+			sequence: ""
+		};
+	}
+
+	let lcs = 0;
+
+	let lastSubIndex = 0;
+
+	let table = [];
+	let len1 = string1.length;
+	let len2 = string2.length;
+	let row;
+	let col;
+
+	/**
+	 * Matrix
+	 * - has an increased dimension to avoid extra checks for previous elements
+	 *
+	 * - the number of rows is equal to the length of the first string + 1
+	 * - the number of columns is equal to the length of the second string + 1
+	 */
+	for (row = 0; row <= len1; row++) {
+		table[row] = [];
+		for (col = 0; col <= len2; col++) {
+			table[row][col] = 0;
+		}
+	}
+
+	// Fill the matrix
+	let i;
+	let j;
+
+	for (i = 0; i < len1; i++) {
+		for (j = 0; j < len2; j++) {
+			if (string1[i] === string2[j]) {
+				// The letters match
+				if (table[i][j] === 0) {
+					table[i + 1][j + 1] = 1;
+				} else {
+					table[i + 1][j + 1] = table[i][j] + 1;
+				}
+
+				// increment lcs if it's needed
+				if (table[i + 1][j + 1] > lcs) {
+					lcs = table[i + 1][j + 1];
+					lastSubIndex = i;
+				}
+			} else {
+				// The letters don't match
+				table[i + 1][j + 1] = 0;
+			}
+		}
+	}
+
+	return {
+		lcs: lcs,
+		offset: lastSubIndex - lcs + 1,
+		sequence: string1.slice(lastSubIndex - lcs + 1, lastSubIndex + 1)
+	};
 }
+
+console.log(lcs("hish", "fish")); // { lcs: 3, offset: 1, sequence: 'ish' }
+console.log(lcs("vista", "hish")); // { lcs: 2, offset: 1, sequence: 'is' }
+console.log(lcs("google", "abcdefgooglehijklm")); // { lcs: 6, offset: 0, sequence: 'google' }
+console.log(lcs("0", 0)); // { lcs: 0, offset: 0, sequence: '' }

09_dynamic_programming/javascript/02_levenstein.js

@@ -0,0 +1,47 @@
+/**
+ * Compute the edit distance between the two given strings
+ *
+ * @param {*} source
+ * @param {*} target
+ *
+ * @return {number}
+ */
+function getEditDistance(source, target) {
+	if (source.length == 0) return target.length;
+	if (target.length == 0) return source.length;
+
+	let i;
+	let j;
+	let matrix = [];
+
+	// Fill the column
+	for (i = 0; i <= target.length; i++) {
+		matrix[i] = [i];
+	}
+
+	// Fill the column
+	for (j = 0; j <= source.length; j++) {
+		matrix[0][j] = j;
+	}
+
+	// Fill in the rest of the matrix
+	for (i = 1; i <= target.length; i++) {
+		for (j = 1; j <= source.length; j++) {
+			if (target.charAt(i - 1) == source.charAt(j - 1)) {
+				matrix[i][j] = matrix[i - 1][j - 1];
+			} else {
+				matrix[i][j] = Math.min(
+					matrix[i - 1][j - 1] + 1, // substitution
+					Math.min(
+						matrix[i][j - 1] + 1, // insertion
+						matrix[i - 1][j] + 1
+					)
+				); // deletion
+			}
+		}
+	}
+
+	return matrix[target.length][source.length];
+}
+
+console.log(getEditDistance("google", "notgoogl")); // 4