66 lines
2.0 KiB
JavaScript
66 lines
2.0 KiB
JavaScript
// https://www.freecodecamp.org/learn/coding-interview-prep/algorithms/implement-quick-sort
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function quickSort(array) {
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// Only change code below this line
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const swap = (array, indexA, indexB) => {
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const temp = array[indexA];
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array[indexA] = array[indexB];
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array[indexB] = temp;
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};
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const medianIndex = (array, indexA, indexB, indexC) => {
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const lowerIndex = array[indexA] < array[indexB] ? indexA : indexB;
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const higherIndex = array[lowerIndex] > array[indexC] ? lowerIndex : indexC;
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const pivotIndex =
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array[indexA] < array[higherIndex] ? indexA : higherIndex;
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return pivotIndex;
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};
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const partition = (array, startIndex, endIndex) => {
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const midIndex = Math.floor(startIndex + (endIndex - startIndex) / 2);
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const pivotIndex = medianIndex(array, startIndex, midIndex, endIndex);
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const pivot = array[pivotIndex];
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swap(array, pivotIndex, endIndex);
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let lowIndex = startIndex;
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let highIndex = endIndex - 1;
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while (lowIndex < highIndex) {
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for (; lowIndex < highIndex; lowIndex++) {
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if (array[lowIndex] > pivot) break;
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}
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for (; highIndex >= lowIndex; highIndex--) {
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if (array[highIndex] < pivot) break;
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}
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if (lowIndex < highIndex) swap(array, lowIndex, highIndex);
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}
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if (array[lowIndex] > array[endIndex]) {
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swap(array, lowIndex, endIndex);
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return lowIndex;
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}
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return endIndex;
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};
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// To-do: make it non-recursive
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const quicksort_ = (array, startIndex, endIndex) => {
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if (startIndex < endIndex) {
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const pivotIndex = partition(array, startIndex, endIndex);
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if (pivotIndex - 1 > startIndex)
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quicksort_(array, startIndex, pivotIndex - 1);
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if (pivotIndex + 1 < endIndex)
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quicksort_(array, pivotIndex + 1, endIndex);
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}
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};
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quicksort_(array, 0, array.length - 1);
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return array;
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// Only change code above this line
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}
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console.log(
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quickSort([
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1, 4, 2, 8, 345, 123, 43, 32, 5643, 63, 123, 43, 2, 55, 1, 234, 92,
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])
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);
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console.log(quickSort([2, 6, 5, 3, 8, 7, 1, 0]));
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