ds-algo-study/DS-n-Algos/Dynamic-Programming/popular-problems/EditDistance.js

Just experimenting with publishing a package

/*
Wikipedia -> https://en.wikipedia.org/wiki/Edit_distance

Q. -> Given two strings `word1` and `word2`. You can perform these operations on any of the string to make both strings similar.
    - Insert
    - Remove
    - Replace
Find the minimum operation cost required to make both same. Each operation cost is 1.

Algorithm details ->
time complexity - O(n*m)
space complexity - O(n*m)
*/

const minimumEditDistance = ( word1, word2 ) => {
  const n = word1.length
  const m = word2.length
  const dp = new Array( m + 1 ).fill( 0 ).map( item => [] )

  /*
    fill dp matrix with default values -
        - first row is filled considering no elements in word2.
        - first column filled considering no elements in word1.
    */

  for ( let i = 0; i < n + 1; i++ ) {
    dp[ 0 ][ i ] = i
  }

  for ( let i = 0; i < m + 1; i++ ) {
    dp[ i ][ 0 ] = i
  }

  /*
        indexing is 1 based for dp matrix as we defined some known values at first row and first column/
    */

  for ( let i = 1; i < m + 1; i++ ) {
    for ( let j = 1; j < n + 1; j++ ) {
      const letter1 = word1[ j - 1 ]
      const letter2 = word2[ i - 1 ]

      if ( letter1 === letter2 ) {
        dp[ i ][ j ] = dp[ i - 1 ][ j - 1 ]
      } else {
        dp[ i ][ j ] = Math.min( dp[ i - 1 ][ j ], dp[ i - 1 ][ j - 1 ], dp[ i ][ j - 1 ] ) + 1
      }
    }
  }

  return dp[ m ][ n ]
}

const main = () => {
  console.log( minimumEditDistance( 'horse', 'ros' ) )
  console.log( minimumEditDistance( 'cat', 'cut' ) )
  console.log( minimumEditDistance( '', 'abc' ) )
  console.log( minimumEditDistance( 'google', 'glgool' ) )
}

main()