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49 changes: 49 additions & 0 deletions Dynamic-Programming/LevenshteinDistance.js
Original file line number Diff line number Diff line change
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/**
* A Dynamic Programming based solution for calculation of the Levenshtein Distance
* https://en.wikipedia.org/wiki/Levenshtein_distance
*/

function minimum (a, b, c) {
if (a < b && a < c) {
return a
} else if (b < a && b < c) {
return b
} else {
return c
}
}

function costOfSubstitution (x, y) {
return x === y ? 0 : 1
}

function calculate (x, y) {
const dp = new Array(x.length + 1)
for (let i = 0; i < x.length + 1; i++) {
dp[i] = new Array(y.length + 1)
}

for (let i = 0; i < x.length + 1; i++) {
for (let j = 0; j < y.length + 1; j++) {
if (i === 0) {
dp[i][j] = j
} else if (j === 0) {
dp[i][j] = i
} else {
dp[i][j] = minimum(dp[i - 1][j - 1] + costOfSubstitution(x.charAt(i - 1), y.charAt(j - 1)), dp[i - 1][j] + 1, dp[i][j - 1] + 1)
}
}
}

return dp[x.length][y.length]
}

function main () {
const x = '' // enter your string here
const y = '' // enter your string here

console.log('Levenshtein distance between ' + x + ' and ' + y + ' is: ')
console.log(calculate(x, y))
}

main()