src/main/java/BonusExercises.java

@@ -20,7 +20,7 @@ public class BonusExercises {
             - Each segment (between dots) must follow same hyphen rules
      */
     public boolean validateEmail(String email) {
-        String regex = ""; // todo
+        String regex = "^[^\\s.@]+(\\.[^\\s.@]+)*@[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);
 
@@ -39,10 +39,50 @@ public class BonusExercises {
         If no match for a date is found in the string, return null.
     */
     public String findDate(String string) {
-        // todo
+        for (int i = 0; i <= string.length() - 10; i++) {
+            if (isValidMonth(string, i) && string.charAt(i+2) == '/' && isValidDay(string, i+3) && string.charAt(i+5) == '/' && isValidYear(string, i+6)) {
+                return string.substring(i, i + 10);
+            }
+            if (isValidDay(string, i) && string.charAt(i+2) == '/' && isValidMonth(string, i+3) && string.charAt(i+5) == '/' && isValidYear(string, i+6)) {
+                return string.substring(i, i + 10);
+            }
+            if (isValidYear(string, i) && string.charAt(i+4) == '-' && isValidMonth(string, i+5) && string.charAt(i+7) == '-' && isValidDay(string, i+8)) {
+                return string.substring(i, i + 10);
+            }
+            if (isValidYear(string, i) && string.charAt(i+4) == '/' && isValidMonth(string, i+5) && string.charAt(i+7) == '/' && isValidDay(string, i+8)) {
+                return string.substring(i, i + 10);
+            }
+        }
         return null;
     }
 
+    private int getInt2(String string, int i) {
+        int n = (string.charAt(i) - '0') * 10 + (string.charAt(i+1) - '0');
+        return n;
+    }
+
+    private int getInt4(String string, int i) {
+        int n = (string.charAt(i) - '0') * 1000 + (string.charAt(i+1) - '0') * 100 + (string.charAt(i+2) - '0') * 10 + (string.charAt(i+3) - '0');
+        return n;
+    }
+
+    private boolean isValidDay(String string, int start) {
+        int d = getInt2(string, start);
+        if (d >= 1 && d <= 31) {return true;}
+        else {return false;}
+    }
+
+    private boolean isValidMonth(String string, int start) {
+        int m = getInt2(string, start);
+        if (m >= 1 && m <= 12) {return true;}
+        else {return false;}
+    }
+
+    private boolean isValidYear(String string, int start) {
+        int y = getInt4(string, start);
+        if (y >= 1 && y <= 9999) {return true;}
+        else {return false;}
+    }
     /*
         given a string, implement the method to detect all valid passwords
         then, it should return the count of them
@@ -54,10 +94,39 @@ public class BonusExercises {
         - has no white-space in it
      */
     public int findValidPasswords(String string) {
-        // todo
+        int count = 0;
-        return -1;
+        String currentWord = "";
+        String input = string + " ";
+
+        for (int i = 0; i < input.length(); i++) {
+            char c = input.charAt(i);
+            if (c == 32 || c == 9 || c == 10 || c == 13) {
+                if (currentWord.length() >= 8) {
+                    if (isValid(currentWord)) {
+                        count++;
+                    }
+                }
+                currentWord = "";
+            } else {
+                currentWord += c;
+            }
+        }
+        return count;
     }
 
+    private boolean isValid(String word) {
+        boolean hasUpper = false, hasLower = false, hasNum = false, hasSpecial = false;
+
+        for (int i = 0; i < word.length(); i++) {
+            char c = word.charAt(i);
+            if (c >= 65 && c <= 90) {hasUpper = true;}
+            else if (c >= 97 && c <= 122) {hasLower = true;}
+            else if (c >= 48 && c <= 57) {hasNum = true;}
+            else if (c == 33 || c == 64 || c == 35 || c == 36 || c == 37 || c == 94 || c == 38 || c == 42) {hasSpecial = true;}
+        }
+        if (hasUpper && hasLower && hasNum && hasSpecial) {return true;}
+        else {return false;}
+    }
     /*
         you should return a list of *words* which are palindromic
         by word we mean at least 3 letters with no whitespace in it
@@ -66,10 +135,37 @@ public class BonusExercises {
      */
     public List<String> findPalindromes(String string) {
         List<String> list = new ArrayList<>();
-        // todo
+        String currentWord = "";
+        String input = string+ " ";
+
+        for (int i = 0; i < input.length(); i++) {
+            char c = input.charAt(i);
+            if (c == 32 || c == 9 || c == 10 || c == 13 || c == 44) {
+                if (currentWord.length() >= 3 && isPalindrome(currentWord)) {
+                    list.add(currentWord);
+                }
+                currentWord = "";
+            } else {
+                currentWord += c;
+            }
+        }
         return list;
     }
 
+    private boolean isPalindrome(String string) {
+        int n = string.length();
+        for (int i = 0; i < n / 2; i++) {
+            char left = string.charAt(i);
+            char right = string.charAt(n - 1 - i);
+            if (left != right) {
+                if (Math.abs(left - right) != 32) {
+                    return false;
+                }
+            }
+        }
+        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 +22,18 @@ 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][];
-        // todo
+        for (int i = 0; i < n; i++) {
-        return null;
+            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 +69,48 @@ public class MainExercises
            - Number of columns: matrix[0].length (if rectangular)
    */
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
+        int m = matrix.length;
-        return null;
+        int n = matrix[0].length;
+        int[] result = new int[m*n];
+        int counter, t = 0, s = 0, k = 0, index = 0;
+
+        if (m > n) {counter = 2 * n;}
+        else if (m == n) {counter = 2 * n - 1;}
+        else {counter = 2 * m - 1;}
+
+        while (t < counter) {
+            if (t < counter) {
+                for (int j = s; j < n - k; j++) {
+                    result[index] = matrix[s][j];
+                    index++;
+                }
+                t++;
+            }
+            if (t < counter) {
+                for (int i = s + 1; i < m - k; i++) {
+                    result[index] = matrix[i][n - 1 - k];
+                    index++;
+                }
+                t++;
+            }
+            if (t < counter) {
+                for (int j = n - 2 - k; j >= s; j--) {
+                    result[index] = matrix[m - 1 - k][j];
+                    index++;
+                }
+                t++;
+            }
+            if (t < counter) {
+                for (int i = m - 2 - k; i > s; i--) {
+                    result[index] = matrix[i][s];
+                    index++;
+                }
+                t++;
+            }
+            s++;
+            k++;
+        }
+        return result;
     }
 
     /*
@@ -91,8 +142,45 @@ public class MainExercises
     */
 
     public int[][] intPartitions(int n) {
-        // todo
+        List<int[]> result = new ArrayList<>();
-        return null;
+        int[] p = new int[n];
+        int k = 1;
+        p[0] = n;
+        result.add(new int[]{n});
+
+        while (true) {
+            int i = k - 1;
+            while (i >= 0 && p[i] == 1) {
+                i--;
+            }
+            if (i < 0) {break;}
+            p[i]--;
+            int remainder = 1;
+            for (int j = i + 1; j < k; j++) {
+                remainder += p[j];
+            }
+            k = i + 1;
+            while (remainder >= p[i]) {
+                p[k] = p[i];
+                remainder -= p[i];
+                k++;
+            }
+            if (remainder > 0) {
+                p[k] = remainder;
+                k++;
+            }
+            int[] part = new int[k];
+            for (int j = 0; j < k; j++) {
+                part[j] = p[j];
+            }
+            result.add(part);
+        }
+
+        int[][] out = new int[result.size()][];
+        for (int i = 0; i < result.size(); i++) {
+            out[i] = result.get(i);
+        }
+        return out;
     }