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choose pivot from median of three elements for quicksort #171

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choose pivot from median of three elements for quicksort #171

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d4af68b
choose pivot from median of three elements for quicksort
larskotthoff Aug 15, 2018
f4668db
Merge branch 'master' into master
larskotthoff Dec 11, 2018
478abba
fix pivot picking and kruskal's algorithm
larskotthoff Dec 11, 2018
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fix pivot picking and kruskal's algorithm
@larskotthoff
larskotthoff committed Dec 11, 2018

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commit 478abbadc93b7a494f7c1f039bee265d372479e0
2 changes: 1 addition & 1 deletion src/algorithms/graph/kruskal/kruskal.js
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Original file line number Diff line number Diff line change
@@ -24,7 +24,7 @@ export default function kruskal(graph) {
*/
compareCallback: (graphEdgeA, graphEdgeB) => {
if (graphEdgeA.weight === graphEdgeB.weight) {
return 1;
return 0;
}

return graphEdgeA.weight <= graphEdgeB.weight ? -1 : 1;
12 changes: 8 additions & 4 deletions src/algorithms/sorting/quick-sort/QuickSort.js
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Original file line number Diff line number Diff line change
@@ -22,11 +22,15 @@ export default class QuickSort extends Sort {
// Take the median element of first, mid, and last elements.
let pivotElement = array[0];
const mid = Math.floor(array.length / 2);
if ((array[mid] < array[array.length - 1] && array[mid] > array[0])
|| (array[mid] > array[array.length - 1] && array[mid] < array[0])) {
if ((this.comparator.lessThan(array[mid], array[array.length - 1])
&& this.comparator.greaterThan(array[mid], array[0]))
|| (this.comparator.greaterThan(array[mid], array[array.length - 1])
&& this.comparator.lessThan(array[mid], array[0]))) {
pivotElement = array[mid];
} else if ((array[array.length - 1] < array[mid] && array[array.length - 1] > array[0])
|| (array[array.length - 1] > array[mid] && array[array.length - 1] < array[0])) {
} else if ((this.comparator.lessThan(array[array.length - 1], array[mid])
&& this.comparator.greaterThan(array[array.length - 1], array[0]))
|| (this.comparator.greaterThan(array[array.length - 1], array[mid])
&& this.comparator.lessThan(array[array.length - 1], array[0]))) {
pivotElement = array[array.length - 1];
}