49 lines
1.4 KiB
JavaScript
49 lines
1.4 KiB
JavaScript
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import React, { useState } from "react";
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function expectedNumMergeSortSteps(n) {
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// https://cs.stackexchange.com/questions/82862/expected-number-of-comparisons-in-a-merge-step
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// n-2 for each step, so (n-2) + (n-2)/2 + (n-2)/4 + ...
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// ~ 2*(n-2) -1 = 2*n - 3
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if (n == 0) {
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return 0;
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} else if (n == 1) {
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return 0;
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} else if (n == 2) {
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return 1;
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} else if (n == 3) {
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return 2;
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} else {
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return (
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Math.ceil(n ** 2 / (n + 2)) + expectedNumMergeSortSteps(Math.ceil(n / 2))
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);
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}
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}
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const firstFewMaxMergeSortSequence = [
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0, 0, 1, 3, 5, 8, 11, 14, 17, 21, 25, 29, 33, 37, 41, 45, 49, 54, 59, 64, 69,
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74, 79, 84, 89, 94, 99, 104, 109, 114, 119, 124, 129, 135, 141, 147, 153, 159,
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165, 171, 177, 183, 189, 195, 201, 207, 213, 219, 225, 231, 237, 243, 249,
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255, 261, 267, 273, 279, 285,
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];
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function maxMergeSortSteps(n) {
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if (n < firstFewMaxMergeSortSequence.length) {
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return firstFewMaxMergeSortSequence[n];
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} else {
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return (
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maxMergeSortSteps(Math.floor(n / 2)) +
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maxMergeSortSteps(Math.ceil(n / 2)) +
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n -
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1
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);
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}
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}
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export function ProgressIndicator({ numStepsNow, numElements }) {
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const expectedNumSteps = expectedNumMergeSortSteps(numElements);
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const maxSteps = maxMergeSortSteps(numElements);
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return (
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<p>{`${numStepsNow} out of ~${expectedNumSteps} (max ${maxSteps}) comparisons`}</p>
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);
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}
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