#### Dice Coefficient

H
```/* The Sørensen–Dice coefficient is a statistic used to gauge the similarity of two samples.
* Applied to strings, it can give you a value between 0 and 1 (included) which tells you how similar they are.
* Dice coefficient is calculated by comparing the bigrams of both strings,
* a bigram is a substring of the string of length 2.
*/

// Time complexity: O(m + n), m and n being the sizes of string A and string B

// Find the bistrings of a string and return a hashmap (key => bistring, value => count)
function mapBigrams(string) {
const bigrams = new Map()
for (let i = 0; i < string.length - 1; i++) {
const bigram = string.substring(i, i + 2)
const count = bigrams.get(bigram)
bigrams.set(bigram, (count || 0) + 1)
}
return bigrams
}

// Calculate the number of common bigrams between a map of bigrams and a string

function countCommonBigrams(bigrams, string) {
let count = 0
for (let i = 0; i < string.length - 1; i++) {
const bigram = string.substring(i, i + 2)
if (bigrams.has(bigram)) count++
}
return count
}

// Calculate Dice coeff of 2 strings
function diceCoefficient(stringA, stringB) {
if (stringA === stringB) return 1
else if (stringA.length < 2 || stringB.length < 2) return 0

const bigramsA = mapBigrams(stringA)

const lengthA = stringA.length - 1
const lengthB = stringB.length - 1

let dice = (2 * countCommonBigrams(bigramsA, stringB)) / (lengthA + lengthB)

// cut 0.xxxxxx to 0.xx for simplicity
dice = Math.floor(dice * 100) / 100

return dice
}

export { diceCoefficient }
```