Done

src/Main.java

@@ -7,9 +7,9 @@
 public class Main {
     public static void main(String[] args) {
 
-        char[] arr = {'a', 'b', 'c'};
-        int target = 2;
-        char[] result = CodingTests.startToLength(arr, 1, 1);
+        int[] arr1 = {1,2};
+        int[] arr2 = null;
+        int[] result = CodingTests.commonToArrays(arr1, arr2);
         System.out.println(Arrays.toString(result));
     }
 

src/maharishi/CodingTests.java

@@ -1,10 +1,14 @@
 // https://compro.miu.edu/sample-test/
 package maharishi;
 
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
 public class CodingTests {
 
     // Find the smallest element in an odd number array
-    public static int smallestOfOddNumArray(int[] nums){
+    public static int smallestOfOddNumArray(int[] nums) {
         // {3, 2, 1, 4, 5}
         // Check if array is not null or length == 0 return 0
         // Check if the array is an odd number array
@@ -14,24 +18,24 @@ public static int smallestOfOddNumArray(int[] nums){
         // middle < at each index
         // return 1, 0 otherwise.
 
-        if (nums ==null || nums.length == 0)
+        if (nums == null || nums.length == 0)
             return 0;
 
-        if (nums.length % 2 ==0)
+        if (nums.length % 2 == 0)
             return 0;
 
         int middleIndex = nums.length / 2;
         int middleElement = nums[middleIndex];
 
-        for (int i = 0; i < nums.length; i++){
-            if (i != middleIndex && middleElement >= nums[i] )
+        for (int i = 0; i < nums.length; i++) {
+            if (i != middleIndex && middleElement >= nums[i])
                 return 0;
         }
         return 1;
     }
 
     // Find the difference of sum of even and odd numbers in an array
-    public static int sumOfEvenOdd(int[] nums){
+    public static int sumOfEvenOdd(int[] nums) {
         // Check if the array is null, return 0
         // Get the sum of even and odd
         // return the difference between them
@@ -40,11 +44,11 @@ public static int sumOfEvenOdd(int[] nums){
         if (nums == null || nums.length == 0)
             return 0;
 
-        while (i < nums.length){
+        while (i < nums.length) {
             if (nums[i] % 2 == 0)
-                sumOfEven +=nums[i];
+                sumOfEven += nums[i];
             else
-                sumOfOdd +=nums[i];
+                sumOfOdd += nums[i];
             i++;
         }
         // odd = X, even = Y so, X - Y
@@ -53,17 +57,71 @@ public static int sumOfEvenOdd(int[] nums){
 
     // Find the set of character arrays that contains length of characters
     // starting at the start index (zero-based)
-    public static char[] startToLength(char[] letters, int start, int length){
+    public static char[] startToLength(char[] letters, int start, int length) {
 
         if (length < 0 || start < 0 ||
-                start + length-1 >= letters.length){
+                start + length - 1 >= letters.length) {
             return null;
         }
-        char[] sub=new char[length];
+        char[] sub = new char[length];
         int right = start + length; // apply sliding window
-        for (int i = start; i < right; i++){
+        for (int i = start; i < right; i++) {
             sub[i - start] = letters[i];
         }
         return sub;
     }
+
+    public static int reverseNumber(int n) {
+        int sign = 1;
+        if (n == 0) return 0;
+
+        if (n < 0) {
+            sign = -1;
+            n = -n;
+        }
+        int rev = 0;
+        while (n != 0) {
+            rev = (rev * 10) + (n % 10); // take the last digit
+            n /= 10; // breaks down the number
+        }
+        return sign * rev;
+    }
+
+    // Find an array containing all elements common to two given arrays containing distinct positive integers
+    public static int[] commonToArrays(int[]nums1, int[] nums2){
+        Set<Integer> keep=new HashSet<>();
+
+        if (nums1 == null || nums2==null)
+            return null;
+
+        Arrays.sort(nums2);
+
+        for (Integer i: nums1){
+            if (isFound(nums2, i)){
+                keep.add(i);
+            }
+        }
+        int j = 0;
+        int[] ans=new int[keep.size()];
+        for (Integer i: keep){
+            ans[j++]= i;
+        }
+        return ans;
+    }
+
+    private static boolean isFound(int[] nums, int target){
+        int start = 0, end = nums.length - 1;
+
+        while (start <= end){
+            int mid = start + (end - start) / 2;
+
+            if (nums[mid] == target)
+                return true;
+            else if (nums[mid] > target)
+                end = mid - 1;
+            else
+                start = mid + 1;
+        }
+        return false;
+    }
 }