Update README.

README.md

@@ -39,12 +39,12 @@
   * [Permutations](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sets/permutations) (with and without repetitions)
   * [Combinations](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sets/combinations) (with and without repetitions)
   * [Fisher–Yates Shuffle](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sets/fisher-yates) - random permutation of a finite sequence
+  * [Longest Common Subsequence](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sets/longest-common-subsequnce) (LCS) 
 * **String**
   * [Levenshtein Distance](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/levenshtein-distance) - minimum edit distance between two sequences
   * [Hamming Distance](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/hamming-distance) - number of positions at which the symbols are different
   * [Knuth–Morris–Pratt Algorithm](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/knuth-morris-pratt) - substring search
   * [Rabin Karp Algorithm](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/rabin-karp) - substring search
-  * [Longest Common Subsequence](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/longest-common-subsequnce) (LCS)
   * [Longest Common Substring](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/longest-common-substring)
 * **Search**
   * [Binary Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/search/binary-search)
@@ -90,7 +90,7 @@
 * **Dynamic Programming**
   * [Fibonacci Number](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/math/fibonacci)
   * [Levenshtein Distance](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/levenshtein-distance) - minimum edit distance between two sequences
-  * [Longest Common Subsequence](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/longest-common-subsequnce) (LCS)
+  * [Longest Common Subsequence](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sets/longest-common-subsequnce) (LCS)
   * [Longest Common Substring](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/string/longest-common-substring)
   * Increasing subsequence
   * Longest Increasing subsequence

src/algorithms/sets/longest-common-subsequnce/__test__/longestCommonSubsequnce.test.js

@@ -0,0 +1,31 @@
+import longestCommonSubsequnce from '../longestCommonSubsequnce';
+
+describe('longestCommonSubsequnce', () => {
+  it('should find longest common subsequence for two strings', () => {
+    expect(longestCommonSubsequnce([''], [''])).toEqual(['']);
+
+    expect(longestCommonSubsequnce([''], ['A', 'B', 'C'])).toEqual(['']);
+
+    expect(longestCommonSubsequnce(['A', 'B', 'C'], [''])).toEqual(['']);
+
+    expect(longestCommonSubsequnce(
+      ['A', 'B', 'C'],
+      ['D', 'E', 'F', 'G'],
+    )).toEqual(['']);
+
+    expect(longestCommonSubsequnce(
+      ['A', 'B', 'C', 'D', 'G', 'H'],
+      ['A', 'E', 'D', 'F', 'H', 'R'],
+    )).toEqual(['A', 'D', 'H']);
+
+    expect(longestCommonSubsequnce(
+      ['A', 'G', 'G', 'T', 'A', 'B'],
+      ['G', 'X', 'T', 'X', 'A', 'Y', 'B'],
+    )).toEqual(['G', 'T', 'A', 'B']);
+
+    expect(longestCommonSubsequnce(
+      ['A', 'B', 'C', 'D', 'A', 'F'],
+      ['A', 'C', 'B', 'C', 'F'],
+    )).toEqual(['A', 'B', 'C', 'F']);
+  });
+});

src/algorithms/sets/longest-common-subsequnce/longestCommonSubsequnce.js

@@ -1,26 +1,26 @@
 /**
- * @param {string} s1
+ * @param {string[]} set1
- * @param {string} s2
+ * @param {string[]} set2
- * @return {string}
+ * @return {string[]}
  */
-export default function longestCommonSubsequnce(s1, s2) {
+export default function longestCommonSubsequnce(set1, set2) {
   // Init LCS matrix.
-  const lcsMatrix = Array(s2.length + 1).fill(null).map(() => Array(s1.length + 1).fill(null));
+  const lcsMatrix = Array(set2.length + 1).fill(null).map(() => Array(set1.length + 1).fill(null));
 
   // Fill first row with zeros.
-  for (let columnIndex = 0; columnIndex <= s1.length; columnIndex += 1) {
+  for (let columnIndex = 0; columnIndex <= set1.length; columnIndex += 1) {
     lcsMatrix[0][columnIndex] = 0;
   }
 
   // Fill first column with zeros.
-  for (let rowIndex = 0; rowIndex <= s2.length; rowIndex += 1) {
+  for (let rowIndex = 0; rowIndex <= set2.length; rowIndex += 1) {
     lcsMatrix[rowIndex][0] = 0;
   }
 
   // Fill rest of the column that correspond to each of two strings.
-  for (let rowIndex = 1; rowIndex <= s2.length; rowIndex += 1) {
+  for (let rowIndex = 1; rowIndex <= set2.length; rowIndex += 1) {
-    for (let columnIndex = 1; columnIndex <= s1.length; columnIndex += 1) {
+    for (let columnIndex = 1; columnIndex <= set1.length; columnIndex += 1) {
-      if (s1[columnIndex - 1] === s2[rowIndex - 1]) {
+      if (set1[columnIndex - 1] === set2[rowIndex - 1]) {
         lcsMatrix[rowIndex][columnIndex] = lcsMatrix[rowIndex - 1][columnIndex - 1] + 1;
       } else {
         lcsMatrix[rowIndex][columnIndex] = Math.max(
@@ -32,19 +32,19 @@ export default function longestCommonSubsequnce(s1, s2) {
   }
 
   // Calculate LCS based on LCS matrix.
-  if (!lcsMatrix[s2.length][s1.length]) {
+  if (!lcsMatrix[set2.length][set1.length]) {
     // If the length of largest common string is zero then return empty string.
-    return '';
+    return [''];
   }
 
-  let lcs = '';
+  const longestSequence = [];
-  let columnIndex = s1.length;
+  let columnIndex = set1.length;
-  let rowIndex = s2.length;
+  let rowIndex = set2.length;
 
   while (columnIndex > 0 || rowIndex > 0) {
-    if (s1[columnIndex - 1] === s2[rowIndex - 1]) {
+    if (set1[columnIndex - 1] === set2[rowIndex - 1]) {
       // Move by diagonal left-top.
-      lcs = s1[columnIndex - 1] + lcs;
+      longestSequence.unshift(set1[columnIndex - 1]);
       columnIndex -= 1;
       rowIndex -= 1;
     } else if (lcsMatrix[rowIndex][columnIndex] === lcsMatrix[rowIndex][columnIndex - 1]) {
@@ -56,5 +56,5 @@ export default function longestCommonSubsequnce(s1, s2) {
     }
   }
 
-  return lcs;
+  return longestSequence;
 }

src/algorithms/string/longest-common-subsequnce/__test__/longestCommonSubsequnce.test.js

@@ -1,13 +0,0 @@
-import longestCommonSubsequnce from '../longestCommonSubsequnce';
-
-describe('longestCommonSubsequnce', () => {
-  it('should find longest common subsequence for two strings', () => {
-    expect(longestCommonSubsequnce('', '')).toBe('');
-    expect(longestCommonSubsequnce('', 'ABC')).toBe('');
-    expect(longestCommonSubsequnce('ABC', '')).toBe('');
-    expect(longestCommonSubsequnce('ABC', 'DEFG')).toBe('');
-    expect(longestCommonSubsequnce('ABCDGH', 'AEDFHR')).toBe('ADH');
-    expect(longestCommonSubsequnce('AGGTAB', 'GXTXAYB')).toBe('GTAB');
-    expect(longestCommonSubsequnce('ABCDAF', 'ACBCF')).toBe('ABCF');
-  });
-});