HW 2

.idea/.name

@@ -0,0 +1 @@
+MainExercises.java

src/main/java/BonusExercises.java

@@ -3,6 +3,10 @@ import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+/*  First Name and Last Name: Hesam Ghazi
+    Student Number: 403222015
+ */
+
 public class BonusExercises {
 
     /*
@@ -20,10 +24,18 @@ public class BonusExercises {
             - Each segment (between dots) must follow same hyphen rules
      */
     public boolean validateEmail(String email) {
-        String regex = ""; // todo
+
+        String regex =
+                "^(?!.*\\.\\.)" +                    // no consecutive dots
+                        "[^.][A-Za-z0-9._%+-]*[^.]@" +      // local part
+                        "(?!-)" +                           // domain can't start with -
+                        "[A-Za-z0-9-]+" +
+                        "(\\.[A-Za-z0-9-]+)*" +             // domain segments
+                        "(?<!-)$";                          // domain can't end with -
+
         Pattern pattern = Pattern.compile(regex);
         Matcher matcher = pattern.matcher(email);
-
+// Returns true only if the entire string matches
         return matcher.matches();
     }
 
@@ -39,10 +51,46 @@ public class BonusExercises {
         If no match for a date is found in the string, return null.
     */
     public String findDate(String string) {
-        // todo
+
+        String regex =
+                "\\b(?:\\d{1,2}/\\d{1,2}/\\d{4}|\\d{4}-\\d{2}-\\d{2}|\\d{4}/\\d{2}/\\d{2})\\b";
+
+        Matcher matcher = Pattern.compile(regex).matcher(string);
+        // Loop through all possible matches in the input string
+        while (matcher.find()) {
+            // Extract the matched date string
+            String date = matcher.group();
+
+            try {
+                // Try to validate ISO format (YYYY-MM-DD)
+                // LocalDate.parse() will throw exception if invalid
+                if (date.contains("-")) {
+                    java.time.LocalDate.parse(date);
+                }
+                // Handle format: YYYY/MM/DD
+                else if (date.matches("\\d{4}/.*")) {
+                    java.time.LocalDate.parse(
+                            date,
+                            java.time.format.DateTimeFormatter.ofPattern("yyyy/MM/dd"));
+                }
+                // Handle format: MM/DD/YYYY (default slash format)
+                else {
+                    java.time.LocalDate.parse(
+                            date,
+                            java.time.format.DateTimeFormatter.ofPattern("MM/dd/yyyy"));
+                }
+
+                return date;
+
+            } catch (Exception e) {
+                // invalid date, continue searching
+            }
+        }
+
         return null;
     }
 
+
     /*
         given a string, implement the method to detect all valid passwords
         then, it should return the count of them
@@ -54,8 +102,29 @@ public class BonusExercises {
         - has no white-space in it
      */
     public int findValidPasswords(String string) {
-        // todo
-        return -1;
+
+        String regex =
+                "^(?=.*[a-z])" +
+                        "(?=.*[A-Z])" +
+                        "(?=.*\\d)" +
+                        "(?=.*[!@#$%^&*])" +
+                        // No whitespace and minimum length 8
+                        "\\S{8,}$";
+
+        Pattern pattern = Pattern.compile(regex);
+        // Assume passwords are separated by whitespace
+        String[] words = string.split("\\s+");
+
+        int count = 0;
+
+        for (String word : words) {
+            // Check whether current token is a valid password
+            if (pattern.matcher(word).matches()) {
+                count++;
+            }
+        }
+
+        return count;
     }
 
     /*
@@ -65,12 +134,56 @@ public class BonusExercises {
         note: your implementation should be case-insensitive, e.g. Aba -> is palindrome
      */
     public List<String> findPalindromes(String string) {
+
         List<String> list = new ArrayList<>();
-        // todo
+        // Split text into words
+        String[] words = string.split("\\s+");
+
+        for (String word : words) {
+
+            // remove punctuation around words
+            String cleaned = word.replaceAll("[^A-Za-z]", "");
+
+            if (cleaned.length() < 3) {
+                continue;
+            }
+
+            String lower = cleaned.toLowerCase();
+
+            boolean palindrome = true;
+
+            for (int i = 0; i < lower.length() / 2; i++) {
+                if (lower.charAt(i) != lower.charAt(lower.length() - 1 - i)) {
+                    palindrome = false;
+                    break;
+                }
+            }
+
+            if (palindrome) {
+                list.add(cleaned);
+            }
+        }
+
         return list;
     }
 
+
     public static void main(String[] args) {
-        // you can test your code here
+
+        BonusExercises ex = new BonusExercises();
+
+        System.out.println(ex.validateEmail("john.doe@gmail.com"));
+        System.out.println(ex.validateEmail(".john@gmail.com"));
+
+        System.out.println(
+                ex.findDate("Meeting on 2025-07-15 at noon"));
+
+        System.out.println(
+                ex.findValidPasswords(
+                        "abc Test123! Password1@ weakpass HELLO123!"));
+
+        System.out.println(
+                ex.findPalindromes(
+                        "Anna level racecar hello Madam kayak"));
     }
 }

src/main/java/MainExercises.java

@@ -1,4 +1,10 @@
+import java.util.List;
+import java.util.ArrayList;
 public class MainExercises
+
+    /* first Name and last Name: Hesam Ghazi
+    Student Number: 403222015
+     */
 {
     /*
     you should create a triangle with "*" and return a two-dimensional array of characters based on that
@@ -19,9 +25,43 @@ 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) {
+        char[][] triangle = new char[n][];
+// For n <= 3 the examples show a completely filled triangle.
+        if (n <= 3) {
+            for (int i = 0; i < n; i++) {
+                // Allocate row i with length i+1
+                triangle[i] = new char[i + 1];
+                for (int j = 0; j <= i; j++) {
+                    triangle[i][j] = '*';
+                }
+            }
+            return triangle;
+        }
+        // For n > 3, i build a hollow triangle
+        for (int i = 0; i < n; i++) {
+            // Allocate row i
+            triangle[i] = new char[i + 1];
+            // Initialize all positions with spaces
+            for (int j = 0; j <= i; j++) {
+                triangle[i][j] = ' ';
+            }
+            // First row contains only one star
+            if (i == 0) {
+                triangle[i][0] = '*';
+            // Last row is completely filled with stars
+            } else if (i == n - 1) {
+                for (int j = 0; j <= i; j++) {
+                    triangle[i][j] = '*';
+                }
+            }
+            // Middle rows contain stars only at the boundaries
+            else {
+                triangle[i][0] = '*';
+                triangle[i][i] = '*';
+            }
+        }
 
-        // todo
-        return null;
+        return triangle;
 
     }
 
@@ -58,8 +98,51 @@ public class MainExercises
            - Number of columns: matrix[0].length (if rectangular)
    */
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
-        return null;
+        if (matrix == null || matrix.length == 0) {
+            return new int[0];
+        }
+
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+        // Result array will contain every matrix element exactly once
+        int[] result = new int[rows * cols];
+        int index = 0;
+        // Here i define the current boundaries of the spiral
+        int top = 0;
+        int bottom = rows - 1;
+        int left = 0;
+        int right = cols - 1;
+
+        while (top <= bottom && left <= right) {
+            // Traverse top row from left to right
+            for (int j = left; j <= right; j++) {
+                result[index++] = matrix[top][j];
+            }
+            top++;
+            // Traverse right column from top to bottom
+            for (int i = top; i <= bottom; i++) {
+                result[index++] = matrix[i][right];
+            }
+            right--;
+            // Traverse bottom row from right to left
+            // Only if a valid row remains
+            if (top <= bottom) {
+                for (int j = right; j >= left; j--) {
+                    result[index++] = matrix[bottom][j];
+                }
+                bottom--;
+            }
+            // Traverse left column from bottom to top
+            // Only if a valid column remains
+            if (left <= right) {
+                for (int i = bottom; i >= top; i--) {
+                    result[index++] = matrix[i][left];
+                }
+                left++;
+            }
+        }
+
+        return result;
     }
 
     /*
@@ -91,13 +174,64 @@ public class MainExercises
     */
 
     public int[][] intPartitions(int n) {
-        // todo
-        return null;
+        // Stores all partitions that are generated
+        List<int[]> partitions = new ArrayList<>();
+        // Start recursive generation
+        generatePartitions(n, n, new ArrayList<>(), partitions);
+
+        int[][] result = new int[partitions.size()][];
+
+        for (int i = 0; i < partitions.size(); i++) {
+            result[i] = partitions.get(i);
+        }
+
+        return result;
+    }
+
+    private void generatePartitions(
+            int remaining,
+            int max,
+            List<Integer> current,
+            List<int[]> result) {
+
+        if (remaining == 0) {
+
+            int[] partition = new int[current.size()];
+
+            for (int i = 0; i < current.size(); i++) {
+                partition[i] = current.get(i);
+            }
+
+            result.add(partition);
+            return;
+        }
+
+        for (int i = Math.min(max, remaining); i >= 1; i--) {
+
+            current.add(i);
+
+            generatePartitions(
+                    remaining - i,
+                    i,
+                    current,
+                    result);
+
+            current.remove(current.size() - 1);
+        }
     }
 
 
-    public static void main()
-    {
+    public static void main(String[] args) {
 
+        MainExercises ex = new MainExercises();
+
+        int[][] parts = ex.intPartitions(4);
+
+        for (int[] p : parts) {
+            for (int x : p) {
+                System.out.print(x + " ");
+            }
+            System.out.println();
+        }
     }
 }