Created
July 19, 2024 19:41
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iterative mergesort
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| function mergeSort(array, start, end) { | |
| if (array.length <= 1) return array; | |
| let slices = [] | |
| let nextSlices = [] | |
| let nextSlicesTemp = [] | |
| let unit = 2 // then 4 then 8 and so on | |
| const mid = Math.floor((start + end) / 2); | |
| if(mid + 1 <= end) { | |
| slices.push({ | |
| start: mid + 1, | |
| end, | |
| arr: array.slice(mid + 1, end + 1) | |
| }) | |
| } | |
| slices.push({ | |
| start, | |
| end: mid, | |
| arr: array.slice(start, mid + 1) | |
| }) | |
| while(slices.length) { | |
| const slice = slices.pop() | |
| if(slice.end > slice.start) { | |
| const mid = Math.floor((slice.start + slice.end) / 2); | |
| if(mid + 1 <= slice.end) { | |
| slices.push({ | |
| start: mid + 1, | |
| end: slice.end, | |
| arr: array.slice(mid + 1, slice.end + 1) | |
| }) | |
| } | |
| slices.push({ | |
| start: slice.start, | |
| end: mid, | |
| arr: array.slice(slice.start, mid + 1) | |
| }) | |
| } | |
| if(slice.end == slice.start) { | |
| nextSlices.push(slice) | |
| } | |
| } | |
| while(nextSlices.length > 1) { | |
| let max_i = 0 | |
| for(let i = 1; i < nextSlices.length; i += 2) { | |
| const prev = nextSlices[i-1] | |
| const curr = nextSlices[i] | |
| nextSlicesTemp.push({ | |
| start: prev.start, | |
| end: curr.end, | |
| arr: merge(prev.arr, curr.arr) | |
| }) | |
| max_i = i | |
| } | |
| if(max_i < nextSlices.length) { | |
| while(max_i+1 < nextSlices.length) { | |
| nextSlicesTemp.push(nextSlices[++max_i]) | |
| } | |
| } | |
| nextSlices = nextSlicesTemp | |
| unit *= 2 | |
| nextSlicesTemp = [] | |
| max_i = 0 | |
| } | |
| return nextSlices[0].arr | |
| } | |
| function merge(left, right) { | |
| let result = [], leftIndex = 0, rightIndex = 0; | |
| while (leftIndex < left.length && rightIndex < right.length) { | |
| if (left[leftIndex] < right[rightIndex]) { | |
| result.push(left[leftIndex]); | |
| leftIndex++; | |
| } else { | |
| result.push(right[rightIndex]); | |
| rightIndex++; | |
| } | |
| } | |
| return result.concat(left.slice(leftIndex)).concat(right.slice(rightIndex)); | |
| } | |
| mergeSort([0,1,2,3,6,5,4,7,8, -1, -3], 0, 10) |
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