implement a merge sort algorithm JS
// Merge Sort (Recursive)
function mergeSort (unsortedArray) {
// No need to sort the array if the array only has one element or empty
if (unsortedArray.length <= 1) {
return unsortedArray;
}
// In order to divide the array in half, we need to figure out the middle
const middle = Math.floor(unsortedArray.length / 2);
// This is where we will be dividing the array into left and right
const left = unsortedArray.slice(0, middle);
const right = unsortedArray.slice(middle);
// Using recursion to combine the left and right
return merge(
mergeSort(left), mergeSort(right)
);
}
function merge(left, right) {
const resultArray = []
let leftIndex = 0
let rightIndex = 0
while (leftIndex < left.length && rightIndex < right.length) {
if (left[leftIndex] < right[rightIndex]) {
resultArray.push(left[leftIndex])
leftIndex+=1
} else {
resultArray.push(right[rightIndex])
rightIndex+=1
}
}
return resultArray
.concat(left.slice(leftIndex))
.concat(right.slice(rightIndex))
}
function mergeSort(unsortedArray) {
if (unsortedArray.length <= 1) {
return unsortedArray;
}
const middle = Math.floor(unsortedArray.length / 2);
const left = unsortedArray.slice(0, middle);
const right = unsortedArray.slice(middle);
return merge(
mergeSort(left), mergeSort(right)
);
}
mergeSort([10, 9, 8, 7, 6, 5, 4, 3, 2, 1])