Create CountingSortIntegers.java

Sorts/CountingSortIntegers.java

@@ -0,0 +1,66 @@
+/**
+ *
+ * @author Youssef Ali (https://github.com/youssefAli11997)
+ *
+ */
+
+class CountingSortIntegers {
+
+    /**
+     * This method implements the Counting Sort for integers
+     *
+     * @param array The array to be sorted 
+     * @param last The count of total number of elements in array
+     * Sorts the array in increasing order
+     * It sorted only integer arrays especially positive integers
+     * It uses array elements as indexes in the frequency array
+     * Can accept only array elements within the range [0:10^8]
+     **/
+
+    public static void CSI(int array[], int last) {
+    
+    	// The frequency array. It's initialized with zeros
+    	int[] frequency = new int[100000001];
+    	// The final output array
+    	int[] sortedArray = new int[array.length];
+    	int index = 0;
+    	
+    	// Counting the frequency of @param array elements
+    	for(int i=0; i<last; i++){
+    		frequency[array[i]]++;
+    	}
+    	
+    	// Filling the sortedArray
+    	for(int i=0; i<frequency.length; i++){
+    		for(int j=0; j<frequency[i]; j++)
+    			sortedArray[index++] = i;
+    	}
+    	
+    	for(int i=0; i<array.length; i++){
+    		array[i] = sortedArray[i];
+    	}
+    }
+
+    // Driver Program
+    public static void main(String[] args) {
+        // Integer Input
+        int[] arr1 = {4,23,6,78,1,54,231,9,12};
+        int last = arr1.length;
+        
+        System.out.println("Before Sorting:");
+        for (int i=0;i<arr1.length;i++) {
+            System.out.print(arr1[i] + " ");
+        }
+        System.out.println();
+
+        CSI(arr1, last);
+
+        // Output => 1 4 6 9 12 23 54 78 231
+        System.out.println("After Sorting:");
+        for (int i=0;i<arr1.length;i++) {
+            System.out.print(arr1[i] + " ");
+        }
+        System.out.println();
+
+    }
+}