67 lines
1.7 KiB
Java
67 lines
1.7 KiB
Java
/**
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*
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* @author Youssef Ali (https://github.com/youssefAli11997)
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*
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*/
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class CountingSortIntegers {
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/**
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* This method implements the Counting Sort for integers
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*
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* @param array The array to be sorted
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* @param last The count of total number of elements in array
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* Sorts the array in increasing order
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* It sorted only integer arrays especially positive integers
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* It uses array elements as indexes in the frequency array
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* Can accept only array elements within the range [0:10^8]
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**/
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public static void CSI(int array[], int last) {
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// The frequency array. It's initialized with zeros
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int[] frequency = new int[100000001];
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// The final output array
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int[] sortedArray = new int[array.length];
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int index = 0;
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// Counting the frequency of @param array elements
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for(int i=0; i<last; i++){
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frequency[array[i]]++;
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}
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// Filling the sortedArray
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for(int i=0; i<frequency.length; i++){
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for(int j=0; j<frequency[i]; j++)
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sortedArray[index++] = i;
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}
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for(int i=0; i<array.length; i++){
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array[i] = sortedArray[i];
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}
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}
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// Driver Program
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public static void main(String[] args) {
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// Integer Input
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int[] arr1 = {4,23,6,78,1,54,231,9,12};
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int last = arr1.length;
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System.out.println("Before Sorting:");
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for (int i=0;i<arr1.length;i++) {
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System.out.print(arr1[i] + " ");
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}
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System.out.println();
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CSI(arr1, last);
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// Output => 1 4 6 9 12 23 54 78 231
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System.out.println("After Sorting:");
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for (int i=0;i<arr1.length;i++) {
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System.out.print(arr1[i] + " ");
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}
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System.out.println();
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}
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}
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