src/main/java/BonusExercises.java

@@ -1,5 +1,10 @@
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -20,7 +25,13 @@ public class BonusExercises {
             - Each segment (between dots) must follow same hyphen rules
      */
     public boolean validateEmail(String email) {
-        String regex = ""; // todo
+        if (email == null) return false;
+
+        String regex =
+                "^[A-Za-z0-9_+&*-]+(?:\\.[A-Za-z0-9_+&*-]+)*@" +
+                        "(?:[A-Za-z0-9](?:[A-Za-z0-9-]*[A-Za-z0-9])?\\.)+" +
+                        "[A-Za-z0-9](?:[A-Za-z0-9-]*[A-Za-z0-9])?$";
+
         Pattern pattern = Pattern.compile(regex);
         Matcher matcher = pattern.matcher(email);
 
@@ -39,7 +50,34 @@ public class BonusExercises {
         If no match for a date is found in the string, return null.
     */
     public String findDate(String string) {
-        // todo
+        if (string == null) {
+            return null;
+        }
+
+        Pattern pattern = Pattern.compile("\\b\\d{2,4}[/-]\\d{1,2}[/-]\\d{1,4}\\b");
+        Matcher matcher = pattern.matcher(string);
+
+        Map<String, DateTimeFormatter> formattersMap = new LinkedHashMap<>();
+
+        formattersMap.put("yyyy-MM-dd", DateTimeFormatter.ofPattern("yyyy-MM-dd"));
+        formattersMap.put("yyyy/M/d", DateTimeFormatter.ofPattern("yyyy/M/d"));
+        formattersMap.put("M/d/yyyy", DateTimeFormatter.ofPattern("M/d/yyyy"));
+        formattersMap.put("d/M/yyyy", DateTimeFormatter.ofPattern("d/M/yyyy"));
+
+        while (matcher.find()) {
+            String candidate = matcher.group();
+            for (Map.Entry<String, DateTimeFormatter> entry : formattersMap.entrySet()) {
+                String patternStr = entry.getKey();
+                DateTimeFormatter formatter = entry.getValue();
+
+                try {
+                    LocalDate.parse(candidate, formatter);
+                    return candidate;
+
+                } catch (DateTimeParseException ignored) {
+                }
+            }
+        }
         return null;
     }
 
@@ -54,8 +92,52 @@ public class BonusExercises {
         - has no white-space in it
      */
     public int findValidPasswords(String string) {
-        // todo
-        return -1;
+        if(string == null || string.isEmpty()){
+            return 0;
+        }
+        int validPasswordCount = 0;
+        Pattern pattern = Pattern.compile("[A-Za-z0-9!@#$%^&*]+");
+        Matcher matcher = pattern.matcher(string);
+
+        while (matcher.find()){
+            String candidate = matcher.group();
+            if(isValidPassword(candidate)){
+                validPasswordCount ++;
+            }
+        }
+
+        return validPasswordCount;
+    }
+
+    public boolean isValidPassword(String password){
+        if(password.length()<8){
+            return false;
+        }
+
+        boolean hasUpperCase = false;
+        boolean hasLowerCase = false;
+        boolean hasDigit = false;
+        boolean hasSpecialChar = false;
+        String sepecialChras = "!@#$%^&*";
+
+        for( char c : password.toCharArray()){
+            if(Character.isUpperCase(c)){
+                hasUpperCase = true;
+            }
+            else if(Character.isLowerCase(c)){
+                hasLowerCase = true;
+            }
+            else if(Character.isDigit(c)){
+                hasDigit = true;
+            }
+            else if(sepecialChras.indexOf(c) != -1){
+                hasSpecialChar = true;
+            }
+            else if (Character.isSpaceChar(c)){
+                return false;
+            }
+        }
+        return hasUpperCase && hasLowerCase && hasDigit && hasSpecialChar;
     }
 
     /*
@@ -66,11 +148,37 @@ public class BonusExercises {
      */
     public List<String> findPalindromes(String string) {
         List<String> list = new ArrayList<>();
-        // todo
+
+        if (string == null || string.isEmpty()) {
+            return list;
+        }
+
+        String[] words = string.split("\\s+");
+
+        for(String word : words){
+            word = word.replaceAll("^[^a-zA-Z0-9]+|[^a-zA-Z0-9]+$" , "");
+
+            if(word.length() >= 3 && isPalindrome(word)){
+                list.add(word);
+            }
+        }
         return list;
     }
 
+    private boolean isPalindrome(String word){
+        String lower = word.toLowerCase();
+        int left = 0 ,right = lower.length()-1;
+
+        while(left < right) {
+            if (lower.charAt(left) != lower.charAt(right)) {
+                return false;
+            }
+            left++;
+            right--;
+        }
+        return true;
+    }
+
     public static void main(String[] args) {
-        // you can test your code here
     }
 }

src/main/java/MainExercises.java

@@ -1,3 +1,6 @@
+import java.util.ArrayList;
+import java.util.List;
+
 public class MainExercises
 {
     /*
@@ -19,10 +22,16 @@ public class MainExercises
     the output has to be a two-dimensional array of characters, so don't just print the triangle!
  */
     public char[][] generateTriangle(int n) {
-
-        // todo
-        return null;
-
+        char[][] triangle = new char[n][];
+        for (int i = 0; i < n; i++) {
+            triangle[i] = new char[i+1];
+            for (int j = 0; j <=i ; j++) {
+                if(i == 0 || j == 0 || i == j || i == n-1)
+                    triangle[i][j] = '*';
+                else triangle[i][j] = ' ';
+            }
+        }
+        return triangle;
     }
 
 
@@ -58,8 +67,51 @@ public class MainExercises
            - Number of columns: matrix[0].length (if rectangular)
    */
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
-        return null;
+
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+        int total_element = rows * cols;
+        int [] result = new int[total_element];
+        int index = 0;
+
+        int top = 0;
+        int bottom = rows - 1;
+        int left = 0;
+        int right = cols - 1;
+
+        //Direction codes : 0 = right, 1 = down , 2 = left , 3 = up
+        int direction = 0;
+
+        while (top <= bottom && left <= right) {
+            switch (direction){
+                case 0 :
+                    for (int i = left; i <= right ; i++) {
+                        result[index++] = (matrix[top][i]);
+                    }
+                    top++;
+                    break;
+                case 1 :
+                    for (int i = top; i <=bottom ; i++) {
+                        result[index++] = (matrix[i][right]);
+                    }
+                    right--;
+                    break;
+                case 2 :
+                    for (int i = right; i >=left ; i--) {
+                        result[index++] = (matrix[bottom][i]);
+                    }
+                    bottom--;
+                    break;
+                case 3 :
+                    for (int i = bottom; i >=top ; i--) {
+                        result[index++] = (matrix[i][left]);
+                    }
+                    left++;
+                    break;
+            }
+            direction = (direction + 1) % 4;
+        }
+        return result;
     }
 
     /*
@@ -91,10 +143,42 @@ public class MainExercises
     */
 
     public int[][] intPartitions(int n) {
-        // todo
-        return null;
+        List<List<Integer>> allpartitions = new ArrayList<>();
+        List<Integer> currentpartition = new ArrayList<>();
+
+        findpartitionrecursive(n, n, currentpartition, allpartitions);
+
+        return convertListToArray(allpartitions);
     }
 
+    private void findpartitionrecursive(int target, int max, List<Integer> currentpartition, List<List<Integer>> allpartitions) {
+
+        if (target == 0) {
+            allpartitions.add(new ArrayList<>(currentpartition));
+            return;
+        }
+
+
+        for (int i = Math.min(target, max); i >= 1; i--) {
+            currentpartition.add(i);
+            findpartitionrecursive(target - i, i, currentpartition, allpartitions);
+            currentpartition.remove(currentpartition.size() - 1);
+        }
+    }
+
+    private int[][] convertListToArray(List<List<Integer>> mylist) {
+        int[][] resultArray = new int[mylist.size()][];
+        for (int i = 0; i < mylist.size(); i++) {
+            List<Integer> innerList = mylist.get(i);
+            resultArray[i] = new int[innerList.size()];
+            for (int j = 0; j < innerList.size(); j++) {
+                resultArray[i][j] = innerList.get(j);
+            }
+        }
+        return resultArray;
+    }
+
+
 
     public static void main()
     {