function mergeSort(arr) { if (arr.length < 2) { // Arrays of length 0 or 1 are sorted by definition. return arr; } const left = arr.slice(0, Math.floor(arr.length / 2)); const right = arr.slice(Math.floor(arr.length / 2), Math.floor(arr.length)); return merge(mergeSort(left), mergeSort(right)); } function merge(arr1, arr2) { const merged = []; let i = 0, j = 0; while (i < arr1.length && j < arr2.length) { if (arr1[i] <= arr2[j]) { merged.push(arr1[i]); i++; } else if (arr2[j] < arr1[i]) { merged.push(arr2[j]); j++; } } merged.push(...arr1.slice(i), ...arr2.slice(j)); return merged; } const deepEqual = require('./deepEqual'); console.log(deepEqual(mergeSort([]), [])); console.log(deepEqual(mergeSort([1]), [1])); console.log(deepEqual(mergeSort([2, 1]), [1, 2])); console.log(deepEqual(mergeSort([7, 2, 4, 3, 1, 2]), [1, 2, 2, 3, 4, 7])); console.log(deepEqual(mergeSort([1, 2, 3, 4, 5, 0]), [0, 1, 2, 3, 4, 5])); console.log( deepEqual( mergeSort([10, 9, 8, 7, 6, 5, 4, 3, 2, 1]), [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], ), ); console.log( deepEqual( mergeSort([98322, 3242, 876, -234, 34, 12331]), [-234, 34, 876, 3242, 12331, 98322], ), );