Add new programs

Author: ShubhSingh

Diff for: mypc/main/java/Merge2SortedArrayInOne.java

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+package main.java;
+
+/**
+ * Cracking the Coding Interview 10.1 Sorted Merge: You are given two sorted
+ * arrays, A and B, where A has a large enough buffer at the end to hold B.
+ * Write a method to merge B into A in sorted order.
+ * 
+ * <p>
+ * Since we know that A has enough buffer at the end, we won't need to allocate
+ * additional space. Our logic should involve simply comparing elements of A and
+ * B and inserting them in order, until we've exhausted all elements in A and in
+ * B. The only issue with this is that if we insert an element into the front of
+ * A, then we'll have to shift the existing elements backwards to make room for
+ * it. It's better to insert elements into the back of the array, where there's
+ * empty space. The code below does just that. It works from the back of A and
+ * B, moving the largest elements to the back of A.
+ * </p>
+ * 
+ * Note that you don't need to copy the contents of A after running out of
+ * elements in B. They are already in place.
+ **/
+public class Merge2SortedArrayInOne {
+
+	private static void merge(int[] a, int[] b, int lastA, int lastB) {
+		int indexA = lastA - 1; /* Index of last element in array a */
+		int indexB = lastB - 1; /* Index of last element in array b */
+		int indexMerged = lastB + lastA - 1; /* end of merged array */
+		/* Merge a and b, starting from the last element in each */
+		while (indexB >= 0) {
+			/* end of a is > than end of b */
+			if (indexA >= 0 && a[indexA] > b[indexB]) {
+				a[indexMerged] = a[indexA]; // copy element
+				indexA--;
+			} else {
+				a[indexMerged] = b[indexB]; // copy element
+				indexB--;
+			}
+			indexMerged--; // move indices
+		}
+	}
+
+	private static void printArray(int[] arr) {
+		for(int i=0;i<arr.length;i++) {
+			System.out.print(arr[i]+" ");
+		}
+		System.out.println();
+	}
+	public static void main(String[] args) {
+		int[] arrOne = {2,5,7,9,12,-1,-1,-1,-1};
+		int[] arrTwo = {8,10,11,13};
+		int lastArrOne = 5;
+		merge(arrOne, arrTwo, lastArrOne, arrTwo.length);
+		printArray(arrOne);
+	}
+
+}