Java-Sort-Algorithms/CountingSort.java at master · mattryanmtl/Java-Sort-Algorithms · GitHub

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importjava.util.Scanner;


/** Class CountingSort **/

publicclassCountingSort

{

privatestaticfinalintMAX_RANGE = 1000000;

/** Counting Sort function **/

publicstaticvoidsort( int[] arr )

 {

intN = arr.length;

if (N == 0)

return;

/** find max and min values **/

intmax = arr[0], min = arr[0];

for (inti = 1; i < N; i++)

 {

if (arr[i] > max)

max = arr[i];

if (arr[i] < min)

min = arr[i];

 }

intrange = max - min + 1;


/** check if range is small enough for count array **/

/** else it might give out of memory exception while allocating memory for array **/

if (range > MAX_RANGE)

 {

System.out.println("\nError : Range too large for sort");

return;

 }


int[] count = newint[range];

/** make count/frequency array for each element **/

for (inti = 0; i < N; i++)

count[arr[i] - min]++;

/** modify count so that positions in final array is obtained **/

for (inti = 1; i < range; i++)

count[i] += count[i - 1];

/** modify original array **/

intj = 0;

for (inti = 0; i < range; i++)

while (j < count[i])

arr[j++] = i + min;

 }

/** Main method **/

publicstaticvoidmain(String[] args)

 {

Scannerscan = newScanner( System.in );

System.out.println("Counting Sort Test\n");

intn, i;

/** Accept number of elements **/

System.out.println("Enter number of integer elements");

n = scan.nextInt();

/** Create integer array on n elements **/

intarr[] = newint[ n ];

/** Accept elements **/

System.out.println("\nEnter "+ n +" integer elements");

for (i = 0; i < n; i++)

arr[i] = scan.nextInt();

/** Call method sort **/

sort(arr);

/** Print sorted Array **/

System.out.println("\nElements after sorting ");

for (i = 0; i < n; i++)

System.out.print(arr[i]+" ");

System.out.println();

 }

}