47 lines
1.4 KiB
JavaScript
47 lines
1.4 KiB
JavaScript
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// https://www.freecodecamp.org/learn/coding-interview-prep/algorithms/implement-merge-sort
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function mergeSort(array) {
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// Only change code below this line
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let merges = Math.floor(array.length / 2);
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let mergeSize = 1;
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let stop = false;
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while (!stop) {
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stop = merges ? false : true;
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const array2 = [];
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for (let i = 0; i <= merges; i++) {
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const leftArrayStart = i * mergeSize * 2;
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const rightArrayStart = leftArrayStart + mergeSize;
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const leftArrayEnd = Math.min(rightArrayStart, array.length);
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const rightArrayEnd = Math.min(rightArrayStart + mergeSize, array.length);
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let leftI = leftArrayStart; // left array pointer
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let rightI = rightArrayStart; // right array pointer
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while (leftI < leftArrayEnd && rightI < rightArrayEnd) {
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if (array[leftI] <= array[rightI]) {
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array2.push(array[leftI++]);
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} else {
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array2.push(array[rightI++]);
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}
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}
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while (leftI < leftArrayEnd) {
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array2.push(array[leftI++]);
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}
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while (rightI < rightArrayEnd) {
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array2.push(array[rightI++]);
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}
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}
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array = array2;
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mergeSize *= 2;
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merges = Math.floor(merges / 2);
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}
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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(mergeSort([4, 2, 1, 6, 5, 3, 0]));
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console.log(
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mergeSort([
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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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