Add ArrayUtility Comments

Week9/Assignment9/src/ArrayUtility.java

@@ -11,15 +11,15 @@ public class ArrayUtility {
 	 * @return 1D array of combine all elements from 2D array
 	 */
 	public static int[] merge(int[][] d) {
-		int length = 0;
-		for(int i = 0;i < d.length;i++)length+=d[i].length;
-		int[] merged_array = new int[length];
-		int current_index = 0;
-		for(int i = 0;i < d.length;i++)for(int j = 0;j < d[i].length;j++) {
-			merged_array[current_index] = d[i][j];
-			current_index++;
+		int length = 0; //Initialize length to store the column as we will pass this to the array constructor
+		for(int i = 0;i < d.length;i++)length+=d[i].length; //SUM of X(nY) = length
+		int[] mergedArray = new int[length]; // Create a new array with size equal to length
+		int currentIndex = 0; //Create a new variable to store the 2D Array Index
+		for(int i = 0;i < d.length;i++)for(int j = 0;j <  d[i].length;j++) { //Loop through every Row and In each iteration of row, loop through every column
+			mergedArray[currentIndex] = d[i][j]; //Set the 2D array element CI to 3D's IJ
+			currentIndex++; //Move the cursor to the next element
 		}
-		return merged_array;
+		return mergedArray;
 	}
 	
 	/** 
@@ -32,10 +32,10 @@ public class ArrayUtility {
 	 */
 	public static int[][] split(int[] d, int n) {
 		if(n<=0) return new int[0][0]; //Return to prevent ArithmeticException: / by zero and negative array index
-		if (d.length%n!=0)return new int[0][0]; //Return, not array is not splittable
-		int[][] splitted_array = new int[n][d.length/n]; //Create the splitted_array array and initialize it
-		for(int i = 0;i < n;i++)for(int j = 0;j<d.length/n;j++)splitted_array[i][j] = d[j*n+i];
-		return splitted_array;
+		if (d.length%n!=0)return new int[0][0]; //Return, empty array, array can't be split into n equal parts
+		int[][] splittedArray = new int[n][d.length/n]; //Create the splitted_array array and initialize it
+		for(int i = 0;i < n;i++)for(int j = 0;j<d.length/n;j++)splittedArray[i][j] = d[j*n+i]; //Loop for n Row and d.length/n column, the position of 2d array is row * ROW_SIZE + column
+		return splittedArray; //send the reference back
 	}
 
 	public static void show(String[] x) {