Draft Assignment6 Solution

group/assignment6/generateMoves.java

@@ -0,0 +1,58 @@
+package Assignment6;
+
+public class generateMoves {
+	public static void main(String[] args) {
+		generateMoves(new int[] { 1, 2, 0, 3 }, new int[] { 3, 1, 2, 0 });
+
+		generateMoves(new int[] { 1, 4, 6, 2, 0, 3 }, new int[] { 3, 1, 2, 6, 4, 0 });
+	}
+
+	/**
+	 * We use arrays to represent parking slots as this is the simplest DS and most convieniet to use and numbers denote
+	 * car IDs and we assume that there is no duplicate car ID e.g elements are always unique and we denote empty car space
+	 * slot a special number '0'.
+	 * The basic idea is to loop over the cars one by one and to see if it's not in the desired final place then we try to
+	 * look for the empty slot '0' and swap it with the car and put the desired car in the current slot. The algorithm takes
+	 * O(n*n) one pass for going over the cars and another pass for trying to find index of 0 but I believe can be enhanced using
+	 * hashmaps.
+	 * @param source initial arrangement of cars in the parking
+	 * @param destination desired arrangement of cars in the parking.
+	 */
+	public static void generateMoves(int source[], int destination[]) {
+		int length = source.length;
+
+		int indexInSrc = -1;
+		int zeroIndex = -1;
+
+		for (int i = 0; i < length; i++) {
+			printState(source);
+			if (destination[i] != 0 && source[i] != destination[i]) {
+				zeroIndex = findIndex(source, 0);
+				swap(source,zeroIndex, i);
+				indexInSrc = findIndex(source, destination[i]);
+				swap(source,i, indexInSrc);
+			}
+		}
+		printState(source);
+	}
+
+	private static void swap(int source[],int index1, int index2) {
+		int temp = source[index1];
+		source[index1] = source[index2];
+		source[index2] = temp;
+	}	
+
+	private static void printState(int array[]) {
+		for (int i : array)
+			System.out.print(i + " ");
+		System.out.println();
+	}
+
+	private static int findIndex(int array[], int val) {
+		for (int i = 0; i < array.length; i++) {
+			if (array[i] == val)
+				return i;
+		}
+		return -1;
+	}
+}