Merge pull request #143 from Alexandrshy/issues-142-formatting-problems-and-example-for-dynamic-programming

Fixed formatting problems, added JSDoc, deleted duplicate example

09_dynamic_programming/ES6/01_longest_common_subsequence.js

@@ -1,54 +1,78 @@
-function createMatrix(rows, cols) {
-  const matrix = new Array(rows);
+/**
+ * Create a matrix
+ * @param {number} rows Number of rows
+ * @param {number} columns ANumber of columns
+ * @returns {Array} Matrix
+ */
+const createMatrix = (rows = 0, columns = 0) => {
+  const matrix = [];
 
-  for (let i = 0; i < matrix.length; i++) {
-    matrix[i] = new Array(cols).fill(0);
+  for (let i = 0; i < rows; i++) {
+    matrix[i] = Array(columns).fill(0);
   }
 
   return matrix;
-}
+};
 
-function substring(a, b) {
-  const cell = createMatrix(a.length + 1, b.length + 1);
-  let lcs = 0;
-  let lastSubIndex = 0;
+/**
+ * Find the longest substring
+ * @param {string} firstWord First word
+ * @param {string} secondWord Second word
+ * @returns {string} The longest substring
+ */
+const longestSubstring = (firstWord = "", secondWord = "") => {
+  const matrix = JSON.parse(
+    JSON.stringify(createMatrix(firstWord.length, secondWord.length))
+  );
+  let sizeSequence = 0;
+  let indexSequence = 0;
 
-  for (let i = 1; i <= a.length; i++) {
-    for (let j = 1; j <= b.length; j++) {
-      if (a[i - 1] === b[j - 1]) {
-        cell[i][j] = cell[i - 1][j - 1] + 1;
+  for (let i = 0; i < firstWord.length; i++) {
+    for (let j = 0; j < secondWord.length; j++) {
+      if (firstWord[i] === secondWord[j]) {
+        matrix[i][j] = (i && j) > 0 ? matrix[i - 1][j - 1] + 1 : 1;
 
-        if (cell[i][j] > lcs) {
-          lcs = cell[i][j];
-          lastSubIndex = i;
+        if (matrix[i][j] >= sizeSequence) {
+          sizeSequence = matrix[i][j];
+          indexSequence = i + 1;
         }
       } else {
-        cell[i][j] = 0;
+        matrix[i][j] = 0;
       }
     }
   }
 
-  return a.slice(lastSubIndex - lcs, lastSubIndex);
-}
+  return firstWord.slice(indexSequence - sizeSequence, indexSequence);
+};
 
-substring("vista", "hish"); // "is"
-substring("fish", "hish"); // "ish"
+longestSubstring("vista", "hish"); // "is"
+longestSubstring("fish", "hish"); // "ish"
 
-function subsequence(a, b) {
-  const cell = createMatrix(a.length + 1, b.length + 1);
-
-  for (let i = 1; i <= a.length; i++) {
-    for (let j = 1; j <= b.length; j++) {
-      if (a[i] === b[j]) {
-        cell[i][j] = cell[i - 1][j - 1] + 1;
+/**
+ * Find the longest common subsequence
+ * @param {string} firstWord First word
+ * @param {string} secondWord Second word
+ * @returns {number} The longest common subsequence
+ */
+const longestCommonSubsequence = (firstWord = "", secondWord = "") => {
+  const matrix = JSON.parse(
+    JSON.stringify(createMatrix(firstWord.length, secondWord.length))
+  );
+  if (matrix.length === 0 || matrix[0].length === 0) return 0;
+  for (let i = 0; i < firstWord.length; i++) {
+    for (let j = 0; j < secondWord.length; j++) {
+      if (firstWord[i] === secondWord[j]) {
+        matrix[i][j] = (i && j) > 0 ? matrix[i - 1][j - 1] + 1 : 1;
       } else {
-        cell[i][j] = Math.max(cell[i - 1][j], cell[i][j - 1]);
+        matrix[i][j] = Math.max(
+          i > 0 ? matrix[i - 1][j] : 0,
+          j > 0 ? matrix[i][j - 1] : 0
+        );
       }
     }
   }
+  return matrix[firstWord.length - 1][secondWord.length - 1];
+};
 
-  return cell[a.length][b.length];
-}
-
-subsequence("fish", "fosh"); // 3
-subsequence("fort", "fosh"); // 2
+longestCommonSubsequence("fish", "fosh"); // 3
+longestCommonSubsequence("fort", "fosh"); // 2

09_dynamic_programming/ES6/examples/base.js

@@ -1,7 +0,0 @@
-export const initializeMatrix = (rows, cols) => {
-  const matrix = [];
-  for (let i = 0; i < rows.length; i += 1) {
-    matrix.push(Array(cols.length).fill(0));
-  }
-  return matrix;
-};

09_dynamic_programming/ES6/examples/diff_two_words.js

@@ -1,27 +0,0 @@
-import { initializeMatrix } from "./base";
-
-const diff = (firstWord, secondWord) => {
-  const arr1 = firstWord.split("");
-  const arr2 = secondWord.split("");
-  const matrix = initializeMatrix(arr1, arr2);
-  for (let i = 0; i < arr1.length; i += 1) {
-    for (let j = 0; j < arr2.length; j += 1) {
-      if (arr1[i] === arr2[j]) {
-        if (i > 0 && j > 0) {
-          matrix[i][j] = matrix[i - 1][j - 1] + 1;
-        } else {
-          matrix[i][j] = 1;
-        }
-      } else {
-        if (i > 0 && j > 0) {
-          matrix[i][j] = Math.max(matrix[i - 1][j], matrix[i][j - 1]);
-        } else {
-          matrix[i][j] = 0;
-        }
-      }
-    }
-  }
-  return matrix[arr1.length - 1][arr2.length - 1];
-};
-
-export default diff;