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51 lines
1.3 KiB
JavaScript
51 lines
1.3 KiB
JavaScript
/**
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* Counting sort is an algorithm for sorting a collection
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* of objects according to keys that are small integers.
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*
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* It is an integer sorting algorithm.
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*
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* Wikipedia: https://en.wikipedia.org/wiki/Counting_sort
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* Animated Visual: https://www.cs.usfca.edu/~galles/visualization/CountingSort.html
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*/
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const countingSort = (arr, min, max) => {
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// Create an auxiliary resultant array
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const res = []
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// Create the freq array
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const count = []
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let len = max - min + 1
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for (let i = 0; i < len; i++) {
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count[i] = 0
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}
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// Populate the freq array
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for (let i = 0; i < arr.length; i++) {
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count[arr[i] - min] += 1
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}
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// Create a prefix sum array out of the freq array
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count[0] -= 1
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for (let i = 1; i < count.length; i++) {
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count[i] += count[i - 1]
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}
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// Populate the result array using the prefix sum array
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for (let i = arr.length - 1; i >= 0; i--) {
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res[count[arr[i] - min]] = arr[i]
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count[arr[i] - min]--
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}
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// Copy the result back to back to original array
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arr = [...res]
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return arr
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}
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/**
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* Implementation of Counting Sort
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*/
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const array = [3, 0, 2, 5, 4, 1]
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// Before Sort
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console.log('\n- Before Sort | Implementation of Counting Sort -')
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console.log(array)
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// After Sort
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console.log('- After Sort | Implementation of Counting Sort -')
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console.log(countingSort(array, 0, 5))
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console.log('\n')
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