merge sort enormous array javascript code example
Example 1: merge sort javascript
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)
);
}
function merge (left, right) {
let resultArray = [], leftIndex = 0, rightIndex = 0;
while (leftIndex < left.length && rightIndex < right.length) {
if (left[leftIndex] < right[rightIndex]) {
resultArray.push(left[leftIndex]);
leftIndex++;
} else {
resultArray.push(right[rightIndex]);
rightIndex++;
}
}
return resultArray
.concat(left.slice(leftIndex))
.concat(right.slice(rightIndex));
}
Example 2: javascript merge sort
const merge = (left, right) => {
const resArr = [];
let leftIdx = 0;
let rightIdx = 0;
while (leftIdx < left.length && rightIdx < right.length) {
left[leftIdx] < right[rightIdx]
? resArr.push(left[leftIdx++])
: resArr.push(right[rightIdx++]);
}
return [...resArr, ...left.slice(leftIdx), ...right.slice(rightIdx)];
};
const mergeSort = arr =>
arr.length <= 1
? arr
: merge(
mergeSort(arr.slice(0, Math.floor(arr.length / 2))),
mergeSort(arr.slice(Math.floor(arr.length / 2)))
);