Finding the longest common consecutive substring between two strings in JavaScript

We are required to write a JavaScript function that takes in two strings. Let’s call them str1 and str2. The function should then find out the longest consecutive string that is common to both the input strings and return that common string.

For example −

If the input strings are −

const str1 = 'ABABC';
const str2 = 'BABCA';

Then the output string should be −

const output = 'BABC';

Example

Following is the code −

const str1 = 'ABABC';
const str2 = 'BABCA';
const findCommon = (str1 = '', str2 = '') => {
   const s1 = [...str1];
   const s2 = [...str2];
   const arr = Array(s2.length + 1).fill(null).map(() => {
      return Array(s1.length + 1).fill(null);
   });
   for (let j = 0; j <= s1.length; j += 1) {
      arr[0][j] = 0;
   }
   for (let i = 0; i <= s2.length; i += 1) {
      arr[i][0] = 0;
   }
   let len = 0;
   let col = 0;
   let row = 0;
   for (let i = 1; i <= s2.length; i += 1) {
      for (let j = 1; j <= s1.length; j += 1) {
         if (s1[j - 1] === s2[i - 1]) {
            arr[i][j] = arr[i - 1][j - 1] + 1;
         }
         else {
            arr[i][j] = 0;
         }
         if (arr[i][j] > len) {
            len = arr[i][j];
            col = j;
            row = i;
         }
      }
   }
   if (len === 0) {
      return '';
   }
   let res = '';
   while (arr[row][col] > 0) {
      res = s1[col - 1] + res;
      row -= 1;
      col -= 1;
   }
   return res;
};
console.log(findCommon(str1, str2));

Output

Following is the output on console −

BABC

AmitDiwan

Published on 11-Dec-2020 09:13:50

• Related Questions & Answers
• Finding longest substring between two same characters JavaScript
• Finding longest consecutive joins in JavaScript
• How to find the longest common substring from more than two strings in Python?
• Finding the longest substring uncommon in array in JavaScript
• Finding shared element between two strings - JavaScript
• SequenceMatcher in Python for Longest Common Substring.
• Longest string consisting of n consecutive strings in JavaScript
• Finding all the longest strings from an array in JavaScript
• Finding the common streak in two arrays in JavaScript
• Find the longest common prefix between two strings after performing swaps on second string in C++
• Finding and returning uncommon characters between two strings in JavaScript
• Program to print the longest common substring using C++
• Finding the longest Substring with At Least n Repeating Characters in JavaScript
• Finding the length of longest vowel substring in a string using JavaScript
• Finding gcd of two strings in JavaScript