Learning MergeSort with JS

 Today I learn MergeSort in JS!

I Learned mergeSort because this is the fastest sorting algorithm, as it takes O(n log n) time, which is better than bubble sort with time complexity O(n^2). At the end, I understood the main logic of MergeSort, the divide-and-conquer method. which means an array pass to merge_sort(arr), it starts by dividing into subarrays until it reaches 1 element of subarray, then it starts sorting it . 

merge-sort.js

function merge_sort(arr, l=0, h=arr.length-1) {

   

    if(l >= h) return

    let m = Math.floor((l + h) / 2)

    merge_sort(arr, l, m)

    merge_sort(arr, m+1, h)

    merge(arr, l, m, h)

}

function merge(arr, l, m, h) {

   

    const tmp = []

    let i=l, j=m+1

    while(i <= m && j <= h) {

        if(arr[i] < arr[j]) tmp.push(arr[i++])

        else tmp.push(arr[j++])

    }

    while(i <= m) tmp.push(arr[i++])

    while(j <= h) tmp.push(arr[j++])

    for(let k=0; k<tmp.length; k++) arr[l+k] = tmp[k]

}

let arr = [4, 2, 6, 5, 8, 9, 6, 4, 1, 0]

merge_sort(arr)

console.log(arr)

thisi@DanishkSinha MINGW64 ~/OneDrive/Desktop/MASM - C/DSA (main)

$ node merge-sort.js

[

  0, 1, 2, 4, 4,

  5, 6, 6, 8, 9

]