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[QuickSort] #algorithms
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import 'dart:math'; | |
class Quick { | |
void swap(List<int> arr, int i, int j) { | |
var temp = arr[i]; | |
arr[i] = arr[j]; | |
arr[j] = temp; | |
} | |
int partition(List<int> arr, int pivot, int left, int right) { | |
var pivotValue = arr[pivot]; | |
var partitionIndex = left; | |
for (var i = left; i < right; i++) { | |
if (arr[i] < pivotValue) { | |
swap(arr, i, partitionIndex); | |
partitionIndex++; | |
} | |
} | |
swap(arr, right, partitionIndex); | |
return partitionIndex; | |
} | |
void step(List<int> arr, int left, int right) { | |
var pivot = null; | |
var partitionIndex = null; | |
if (left < right) { | |
pivot = right; | |
partitionIndex = partition(arr, pivot, left, right); | |
step(arr, left, partitionIndex - 1); | |
step(arr, partitionIndex + 1, right); | |
} | |
} | |
void sort(List<int> arr) { | |
var left = 0; | |
var right = arr.length - 1; | |
step(arr, left, right); | |
} | |
} | |
String readableInt(int x) { | |
var xS = x.toString().split('').reversed.join(); | |
var y = ''; | |
for (var i = 0; i < xS.length; i++) { | |
if (i % 3 == 0 && i != 0) y += '.'; | |
y += xS[i]; | |
} | |
return y.split('').reversed.join(); | |
} | |
void main() { | |
final quick = Quick(); | |
var x = 1000000000; | |
var a = List.generate(x, (_) => Random().nextInt(x)); | |
var w = Stopwatch()..start(); | |
quick.sort(a); | |
var items = readableInt(x); | |
var ms = readableInt(w.elapsedMilliseconds); | |
print('SORTED $items ITEMS IN $ms MS'); | |
w.stop(); | |
} |
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class Quick { | |
swap(arr: number[], i: number, j: number) { | |
var temp = arr[i]; | |
arr[i] = arr[j]; | |
arr[j] = temp; | |
} | |
partition(arr: number[], pivot: number, left: number, right: number) { | |
var pivotValue = arr[pivot]; | |
var partitionIndex = left; | |
for (var i = left; i < right; i++) { | |
if (arr[i] < pivotValue) { | |
this.swap(arr, i, partitionIndex); | |
partitionIndex++; | |
} | |
} | |
this.swap(arr, right, partitionIndex); | |
return partitionIndex; | |
} | |
step(arr: number[], left: number, right: number) { | |
var pivot = null; | |
var partitionIndex = null; | |
if (left < right) { | |
pivot = right; | |
partitionIndex = this.partition(arr, pivot, left, right); | |
this.step(arr, left, partitionIndex - 1); | |
this.step(arr, partitionIndex + 1, right); | |
} | |
} | |
sort(arr: number[]) { | |
var left = 0; | |
var right = arr.length - 1; | |
this.step(arr, left, right); | |
} | |
} | |
function readableInt(x: number): string { | |
var xS = x.toString().split('').reverse().join(''); | |
var y = ''; | |
for (var i = 0; i < xS.length; i++) { | |
if (i % 3 == 0 && i != 0) y += '.'; | |
y += xS[i]; | |
} | |
return y.split('').reverse().join(''); | |
} | |
const quick = new Quick(); | |
const x = 1000; | |
const a = []; | |
for (let i = 0; i < x; i++) { | |
a.push(Math.floor(Math.random() * x)); | |
} | |
var start = Date.now(); | |
quick.sort(a); | |
var end = Date.now(); | |
var items = readableInt(x); | |
var ms = readableInt(end - start); | |
console.log('SORTED ' + items + ' ITEMS IN ' + ms + ' MS'); | |
export { }; | |
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