diff --git a/Sorts/CountingSort.js b/Sorts/CountingSort.js index 2003cfb73..01bfc2b7e 100644 --- a/Sorts/CountingSort.js +++ b/Sorts/CountingSort.js @@ -8,31 +8,38 @@ * Animated Visual: https://www.cs.usfca.edu/~galles/visualization/CountingSort.html */ -function countingSort (arr, min, max) { - let i - let z = 0 +const countingSort = (arr, min, max) => { + // Create an auxiliary resultant array + const res = [] + // Create the freq array const count = [] + let len = max - min + 1 - for (i = min; i <= max; i++) { + for (let i = 0; i < len; i++) { count[i] = 0 } - - for (i = 0; i < arr.length; i++) { - count[arr[i]]++ + // Populate the freq array + for (let i = 0; i < arr.length; i++) { + count[arr[i] - min] += 1 } - - for (i = min; i <= max; i++) { - while (count[i]-- > 0) { - arr[z++] = i - } + // Create a prefix sum array out of the freq array + count[0] -= 1 + for (let i = 1; i < count.length; i++) { + count[i] += count[i - 1] } - + // Populate the result array using the prefix sum array + for (let i = arr.length - 1; i >= 0; i--) { + res[count[arr[i] - min]] = arr[i] + count[arr[i] - min]-- + } + // Copy the result back to back to original array + arr = [...res] return arr } /** -* Implementation of Counting Sort -*/ + * Implementation of Counting Sort + */ const array = [3, 0, 2, 5, 4, 1] // Before Sort console.log('\n- Before Sort | Implementation of Counting Sort -')