diff --git a/src/algorithms/string/longest-common-substring/__test__/longestCommonSubstring.test.js b/src/algorithms/string/longest-common-substring/__test__/longestCommonSubstring.test.js index 55c7d4da..9b64c7ab 100644 --- a/src/algorithms/string/longest-common-substring/__test__/longestCommonSubstring.test.js +++ b/src/algorithms/string/longest-common-substring/__test__/longestCommonSubstring.test.js @@ -7,5 +7,6 @@ describe('longestCommonSubstring', () => { expect(longestCommonSubstring('', 'ABC')).toBe(''); expect(longestCommonSubstring('ABABC', 'BABCA')).toBe('BABC'); expect(longestCommonSubstring('BABCA', 'ABCBA')).toBe('ABC'); + expect(longestCommonSubstring('𐌵𐌵**ABC', '𐌵𐌵--ABC')).toBe('ABC'); }); }); diff --git a/src/algorithms/string/longest-common-substring/longestCommonSubstring.js b/src/algorithms/string/longest-common-substring/longestCommonSubstring.js index 10919bf6..eb4351f4 100644 --- a/src/algorithms/string/longest-common-substring/longestCommonSubstring.js +++ b/src/algorithms/string/longest-common-substring/longestCommonSubstring.js @@ -4,17 +4,20 @@ * @return {string} */ export default function longestCommonSubstring(s1, s2) { + // transform s1 & s2 into arrays to allow handling unicodes as single caracter. + const [a1, a2] = [s1, s2].map(s => Array.from(s)); + // Init the matrix of all substring lengths to use Dynamic Programming approach. - const substringMatrix = Array(s2.length + 1).fill(null).map(() => { - return Array(s1.length + 1).fill(null); + const substringMatrix = Array(a2.length + 1).fill(null).map(() => { + return Array(a1.length + 1).fill(null); }); // Fill the first row and first column with zeros to provide initial values. - for (let columnIndex = 0; columnIndex <= s1.length; columnIndex += 1) { + for (let columnIndex = 0; columnIndex <= a1.length; columnIndex += 1) { substringMatrix[0][columnIndex] = 0; } - for (let rowIndex = 0; rowIndex <= s2.length; rowIndex += 1) { + for (let rowIndex = 0; rowIndex <= a2.length; rowIndex += 1) { substringMatrix[rowIndex][0] = 0; } @@ -23,9 +26,9 @@ export default function longestCommonSubstring(s1, s2) { let longestSubstringColumn = 0; let longestSubstringRow = 0; - for (let rowIndex = 1; rowIndex <= s2.length; rowIndex += 1) { - for (let columnIndex = 1; columnIndex <= s1.length; columnIndex += 1) { - if (s1[columnIndex - 1] === s2[rowIndex - 1]) { + for (let rowIndex = 1; rowIndex <= a2.length; rowIndex += 1) { + for (let columnIndex = 1; columnIndex <= a1.length; columnIndex += 1) { + if (a1[columnIndex - 1] === a2[rowIndex - 1]) { substringMatrix[rowIndex][columnIndex] = substringMatrix[rowIndex - 1][columnIndex - 1] + 1; } else { substringMatrix[rowIndex][columnIndex] = 0; @@ -50,7 +53,7 @@ export default function longestCommonSubstring(s1, s2) { let longestSubstring = ''; while (substringMatrix[longestSubstringRow][longestSubstringColumn] > 0) { - longestSubstring = s1[longestSubstringColumn - 1] + longestSubstring; + longestSubstring = a1[longestSubstringColumn - 1] + longestSubstring; longestSubstringRow -= 1; longestSubstringColumn -= 1; }