Finished RecursiveExrcise
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7 changed files with 372 additions and 1 deletions
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public class MotzkinNumber {
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public static void main(String[] args) {
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for(int i=0;i<=20;i++)System.out.format("%d:%d\n",i,M(i));
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for(int i=0;i<=20;i++)System.out.format("%d:%d%n",i,M(i));
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}
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public static int M(int n) {
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53
Assignment10/src/MyArrayUtil.java
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53
Assignment10/src/MyArrayUtil.java
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import java.util.Arrays;
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public class MyArrayUtil {
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// return the first data inside the array.
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public static int head(int[] a) throws Exception {
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if (a == null)
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throw new Exception("Array is empty! No head.");
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return a[0];
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}
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// return array similar to a, but without the first data.
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public static int[] tail(int[] a) throws Exception {
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if (a == null)
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throw new Exception("Array is empty! No tail.");
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if (a.length == 1)
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return null;
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return Arrays.copyOfRange(a, 1, a.length);
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}
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// create a new array that is like array a, but with x inserted at
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// the front.
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public static int[] addAsFirst(int x, int[] a) {
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int[] ans;
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if (a == null) {
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ans = new int[1];
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ans[0] = x;
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} else {
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ans = new int[a.length + 1];
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ans[0] = x;
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for (int i = 0; i < a.length; i++) {
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ans[i + 1] = a[i];
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}
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}
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return ans;
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}
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// print array contents out.
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public static void print(int[] a) {
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if (a == null) {
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System.out.println("Array is empty!");
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return;
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}
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for (int i = 0; i < a.length; i++) {
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System.out.print(a[i]);
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if (i != a.length - 1) {
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System.out.print(", ");
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} else {
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System.out.println(".");
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}
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}
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}
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}
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165
Assignment10/src/RecursiveExercise.java
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165
Assignment10/src/RecursiveExercise.java
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import java.util.Arrays;
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public class RecursiveExercise {
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// return an array that has all data of ht and n,
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// just like concatenating ht and n.
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public static int[] append(int[] ht, int[] n) throws Exception {
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if (ht == null)
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return n;
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if (n == null)
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return ht;
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int[] l = append(MyArrayUtil.tail(ht), n);
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int head = MyArrayUtil.head(ht);
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return MyArrayUtil.addAsFirst(head, l);
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}
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public static int[] reverse(int[] ht) throws Exception {
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// fill your code here
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if(ht == null) return null;
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if (ht.length == 1)
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return ht.clone();
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int temp = ht[0];
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ht[0] = ht[ht.length - 1];
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ht[ht.length - 1] = temp;
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return recursiveInnerSandwich(reverse(MyArrayUtil.tail(removeLast(ht, new int[ht.length-1], 0))),ht.clone());
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}
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//This method make an array sandwich excluding the bread (index 0 and index last)
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public static int[] recursiveInnerSandwich(int[] src,int[] dest) throws Exception{
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if (src==null)return dest;
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dest[dest.length-src.length-1] = src[0];
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recursiveInnerSandwich(MyArrayUtil.tail(src),dest);
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return dest;
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}
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//Remove the last element
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public static int[] removeLast(int[] ia1,int[] ia2,int i) {
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ia2[i]=ia1[i];
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if (i==ia2.length-1)return ia2;
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return removeLast(ia1,ia2,i+1);
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}
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public static boolean isIn(int x, int[] a) throws Exception {
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// fill your code here
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if (a[0] == x)
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return true;
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if (a.length == 1)
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return false;
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return isIn(x, MyArrayUtil.tail(a.clone()));
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}
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public static boolean subArray(int[] a1, int[] a2) throws Exception {
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// fill your code here
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if (a1 == null)
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return true;
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if (isIn(a1[0], a2))
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return subArray(MyArrayUtil.tail(a1.clone()), a2);
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if (a1.length == 1)
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return true;
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return false;
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}
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public static int[] shift(int[] ht, int n) throws Exception {
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// fill your code here
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if(ht==null)return null;
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if(n==0)return ht;
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int temp = ht[0];
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ht = insertLast(temp,MyArrayUtil.tail(ht));
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return shift(ht,n-1);
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}
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public static int[] insertLast(int val,int[] ia) throws Exception{
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return reverse(MyArrayUtil.addAsFirst(val, reverse(ia)));
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}
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public static void main(String[] args) throws Exception {
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// test append, when appending empty array with {1,2,3}
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int[] a = null;
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int[] b = { 1, 2, 3 };
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int[] ans1 = append(a, b);
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System.out.println("Append - Expected: 1, 2, 3.");
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System.out.print("Get: ");
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MyArrayUtil.print(ans1);
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System.out.println("");
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// test append, when appending 2 non-empty arrays.
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int[] c = { 1, 2, 3 };
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int[] d = { 4, 5, 6 };
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ans1 = append(c, d);
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System.out.println("Append - Expected: 1, 2, 3, 4, 5, 6.");
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System.out.print("Get: ");
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MyArrayUtil.print(ans1);
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System.out.println("");
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// test reverse
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int[] e = { 1, 2, 3, 4, 5 };
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ans1 = reverse(e);
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System.out.println("Reverse - Expected: 5, 4, 3, 2, 1.");
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System.out.print("Get: ");
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MyArrayUtil.print(ans1);
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System.out.println("");
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// test isIn
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boolean b1 = isIn(3, e);
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System.out.println("isIn - Expected: true.");
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System.out.println("Get: " + b1 + ".");
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boolean b2 = isIn(7, e);
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System.out.println("isIn - Expected: false.");
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System.out.println("Get: " + b2 + ".");
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// test subArray
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int[] f = { 1, 3, 5 };
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int[] g = { 1, 2, 3, 4, 5 };
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int[] h = { 1, 2, 3, 4, 5 };
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int[] i = null;
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int[] j = { 1, 4, 5 };
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b1 = subArray(f, g);
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System.out.println("subArray - Expected: true.");
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System.out.println("Get: " + b1 + ".");
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b1 = subArray(g, h);
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System.out.println("subArray - Expected: true.");
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System.out.println("Get: " + b1 + ".");
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b1 = subArray(i, h);
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System.out.println("subArray - Expected: true.");
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System.out.println("Get: " + b1 + ".");
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b1 = subArray(f, j);
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System.out.println("subArray - Expected: false.");
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System.out.println("Get: " + b1 + ".");
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b1 = subArray(h, j);
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System.out.println("subArray - Expected: false.");
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System.out.println("Get: " + b1 + ".");
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// test shift
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int[] k = shift(g, 3);
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System.out.println("shift - Expected: 4, 5, 1, 2, 3.");
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System.out.print("Get: ");
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MyArrayUtil.print(k);
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System.out.println("");
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k = shift(g, 2);
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System.out.println("shift - Expected: 3, 4, 5, 1, 2.");
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System.out.print("Get: ");
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MyArrayUtil.print(k);
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System.out.println("");
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k = shift(g, 8);
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System.out.println("shift - Expected: 4, 5, 1, 2, 3.");
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System.out.print("Get: ");
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MyArrayUtil.print(k);
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System.out.println("");
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k = shift(g, 0);
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System.out.println("shift - Expected: 1, 2, 3, 4, 5.");
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System.out.print("Get: ");
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MyArrayUtil.print(k);
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System.out.println("");
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k = shift(null, 5);
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System.out.println("shift - Expected: Array empty");
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System.out.print("Get: ");
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MyArrayUtil.print(k);
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System.out.println("");
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}
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}
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