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01-leap-year/Main.java

@@ -0,0 +1,11 @@
+class Main {
+public static void main(String[] args) {
+    System.out.println(isLeapYear(2022));
+    System.out.println(isLeapYear(2020));
+    System.out.println(isLeapYear(1900));
+    System.out.println(isLeapYear(2000));
+  }
+  public static boolean isLeapYear(double year) {
+    return year % 4 == 0 && year % 100 == 0 && year % 400 == 0;
+  }
+}

01-leap-year/README.md

@@ -15,23 +15,26 @@
 2. Label each as either correct or incorrect syntax. If incorrect, rewrite below:
   * if (x == y) {
 
-    * **YOUR WRITING HERE**
+    * Correct
 
   * if [x == 10] {
 
-    * **YOUR WRITING HERE**
+    *Incorrect
+    if (x == 10) {
 
   * if x = 10 then {
 
-    * **YOUR WRITING HERE**
+    *Incorrect 
+    if (x == 10)
 
   * if (x equals 42) {
 
-    * **YOUR WRITING HERE**
+    *Incorrect
+    if (x == 42) {
 
   * if (x => y) {
 
-    * **YOUR WRITING HERE**
+    *Correct
 
 
 3. Fix the error in the code below:
@@ -44,5 +47,11 @@
       System.out.println("Mine, too!");
   }
   ```
-
-  * **YOUR WRITING HERE**
+
+  * import java.util.Scanner;
+    Scanner console = new Scanner(System.in);
+    System.out.print("What is your favorite color?");
+    String name = console.next();
+    if (name == "blue") {
+      System.out.println("Mine, too!")
+    }

02-fizzbuzz/Main.java

@@ -0,0 +1,21 @@
+class Main {
+  public static void main(String[] args) {
+    isFizzBuzz();
+  }
+  public static void isFizzBuzz () {
+    for (int i = 0; i < 100; i++) {
+      if (i % 5 == 0 && i % 3 == 0) {
+        System.out.println("FizzBuzz");
+      }
+      else if (i % 5 == 0) {
+        System.out.println("Buzz");
+      }
+      else if (i % 3 == 0) {
+        System.out.println("Fizz");
+      }
+      else {
+        System.out.println(i);
+      }
+    }
+  }
+}

02-fizzbuzz/README.md

@@ -5,20 +5,20 @@
 
 | P  | Q  | P && Q | P \|\| Q |
 |:--:|:--:|:------:|:--------:|
-| T  | T  |        |          |
-| T  | F  |        |          |
-| F  | T  |        |          |
-| F  | F  |        |          |
+| T  | T  |   T    |    T     |
+| T  | F  |   F    |    T     |
+| F  | T  |   F    |    F     |
+| F  | F  |   F    |    F     |
 
 
 2. Prove a version of DeMorgan's Law:
 
 | P  | Q  | P \|\| Q | ! (P \|\| Q) | !P | !Q | !P && !Q |
 |:--:|:--:|:--------:|:------------:|:--:|:--:|:--------:|
-| T  | T  |          |              |    |    |          |
-| T  | F  |          |              |    |    |          |
-| F  | T  |          |              |    |    |          |
-| F  | F  |          |              |    |    |          |
+| T  | T  |     T    |       F      | F  | F  |    F     |
+| T  | F  |     T    |       T      | F  | T  |    F     |
+| F  | T  |     T    |       T      | T  | F  |    F     |
+| F  | F  |     F    |       T      | T  | T  |    T     |
 
 3. What does DeMorgan's state and how did you prove it for the case above?
-  * **YOUR WRITING HERE**
+  *

03-count-quarters/Main.java

@@ -0,0 +1,10 @@
+class Main {
+  public static void main(String[] args) {
+    System.out.println(countQuarters(4984));
+  }
+  public static String countQuarters(int cents) {
+    String coin = Integer.toString(cents);
+    String quarters = coin.substring(coin.length() -2);
+    return quarters;
+  }
+}

03-count-quarters/README.md

@@ -2,4 +2,5 @@
 #### Respond to the following:
 
 1. How do you isolate the ones digit of a number?
-  * **YOUR WRITING HERE**
+  * Convert to string, substring the last digit (the length of the integer - 1)
+  Alternatively, you could % by 10, giving you the remainder, which would be the ones digit.

04-letter-grade/Main.java

@@ -0,0 +1,56 @@
+class Main {
+  public static void main(String[] args) {
+    System.out.println(letterGrade(87));
+  }
+  public static String letterGrade(int grade) {
+    String letter = "";
+    if (grade >= 90) {
+      if (grade % 10 >= 7) {
+        letter = "A+";
+      }
+      else if (grade % 10 >= 3 && grade % 10 <= 6) {
+        letter = "A";
+      }
+      else {
+        letter = "A-";
+      }
+    }
+    else if (grade >= 80 && grade <= 89) {
+      if (grade % 10 >= 7) {
+        letter = "B+";
+      }
+      else if (grade % 10 >= 3 && grade % 10 <= 6) {
+        letter = "B";
+      }
+      else {
+        letter = "B-";
+      }
+    }
+    else if (grade >= 70 && grade <= 79) {
+      if (grade % 10 >= 7) {
+        letter = "C+";
+      }
+      else if (grade % 10 >= 3 && grade % 10 <= 6) {
+        letter = "C";
+      }
+      else {
+        letter = "C-";
+      }
+    }
+    else if (grade >= 60 && grade <= 69) {
+      if (grade % 10 >= 7) {
+        letter = "D+";
+      }
+      else if (grade % 10 >= 3 && grade % 10 <= 6) {
+        letter = "D";
+      }
+       else  {
+         letter = "D-";
+       }
+    }
+    else if (grade < 60) {
+      letter = "F";
+    }
+    return letter;
+  }
+}

04-letter-grade/README.md

@@ -5,12 +5,12 @@
   * Attach a "+" on their grade if the grade ends in a 7, 8 or 9 (eg: 78 -> C+, 89 -> B+)
   * Attach a "-" on their grade if the grade ends in a 0, 1 or 2 (eg: 92 -> A-, 61 -> D-)
 
-    * **YOUR WRITING HERE**
+    * % by 100, then have if statements for + and -
 
 
 2. Discuss how you would make sure 100 is not misrepresented as an A-.
-  * **YOUR WRITING HERE**
+  * Add if (grade = 100), make it return A+
 
 
 3. Discuss how you would make sure grades that are an F are not mislabeled as F- or F+ (eg: 49 -> F+ and 52 -> F-)
-  * **YOUR WRITING HERE**
+  * Add if (grade < 60), make it always return F if the grade is under 60

05-div-by-3/Main.java

@@ -0,0 +1,18 @@
+class Main {
+  public static void main(String[] args) {
+    System.out.println(divBy3(181));
+    System.out.println(divBy3(35));
+    System.out.println(divBy3(0));
+    System.out.println(divBy3(57));
+    System.out.println(divBy3(21));
+  }
+  public static boolean divBy3 (int number) {
+    int addition = 0;
+    String numint = Integer.toString(number); // convert to string
+    for (int i = 0; i < numint.length(); i++) { // loop number check for string length
+      char check = numint.charAt(i);
+      addition += check; // adds all digits
+    }
+    return addition % 3 == 0; // returns true or false (true = divisible, false = not divisible)
+  }
+}

05-div-by-3/README.md

@@ -4,6 +4,12 @@
 1. A number is considered *prime* if its only factors are 1 and itself. For example, 7 is prime (1 and 7 are the only factors) and 9 is not (1, 3 and 9 are factors).  
 Outline an algorithm to determine whether or not a number is prime.  
 Think of the following method header:
-`public static boolean isPrime(int num)`
-
-  * **YOUR WRITING HERE**
+public static boolean isPrime(int num) {
+    if (num % 2 == 0) {
+      return false;
+    }
+    else {
+      return num % 3 != 0 || num % 5 != 0 || num % 7 != 0 || num % 11 != 0;
+    }
+  }
+}

06-shapes/README.md

@@ -7,7 +7,18 @@
 000111222333444555666777888999
 000111222333444555666777888999
 ```
-  * **YOUR WRITING HERE**
+  *   public static String shapeNum(int num) {
+    String newString = "";
+    String num2 = Integer.toString(num);
+    for (int i = 0; i < num2.length();i++) {
+      for (int j = 0; j < 3; j++) {
+        String temp = num2.substring(i, i + 1);
+        newString += temp;
+      }
+    }
+    return newString;
+  }
+}
 
 
 2. Write a plan for the following output:
@@ -18,4 +29,16 @@
 999998888877777666665555544444333332222211111
 999998888877777666665555544444333332222211111
 ```
-  * **YOUR WRITING HERE**
+(assuming that num = 987654321
+  *   public static String shapeNum(int num) {
+    String newString = "";
+    String num2 = Integer.toString(num);
+    for (int i = 0; i < num2.length();i++) {
+      for (int j = 0; j < 5; j++) {
+        String temp = num2.substring(i, i + 1);
+        newString += temp;
+      }
+    }
+    return newString;
+  }
+}

07-string-puzzles/Main.java

@@ -0,0 +1,17 @@
+//divide word in half
+class Main {
+  public static void main(String[] args) {
+  firstHalf("WooHoo");
+  }
+  public static void firstHalf(String word1) {
+    if (word1.length() % 2 == 0) {
+      int length = word1.length();
+      int div1 = length/2;
+      String word2 = word1.substring(0, div1);
+      System.out.println(word2);
+    }
+    else {
+      System.out.print("Not divisible");
+    }
+  }
+}

07-string-puzzles/Main2.java

@@ -0,0 +1,15 @@
+//count hi in string
+class Main2 {
+  public static void main(String[] args) {
+    System.out.print(countHi("jjdfkjiHI"));
+  }
+  public static int countHi(String str) {
+    int count = 0;
+    for (int i = 0; i <= str.length() - 2; i++) {
+      if (str.substring(i, i + 2).equalsIgnoreCase("hi")) {
+        count++;
+      }
+    }
+    return count;
+  }
+}

07-string-puzzles/Main3.java

@@ -0,0 +1,19 @@
+//letterswap
+class Main3 {
+  public static void main(String[] args) {
+    System.out.println(mysteryMethod("walk", "w", "ch"));
+  }
+  public static String mysteryMethod(String s, String r, String a) {
+    String newString = "";
+    for (int i = 0; i < s.length(); i++) {
+      String character = s.substring(i, i + 1);
+      if (character.equals(r)) {
+        newString += a;
+      }
+      else {
+        newString += character;
+      }
+    }
+    return newString;
+  }
+}

07-string-puzzles/README.md

@@ -3,16 +3,16 @@
 
 1. *In your own words*, discuss what each String method does:
   * `.substring(a)`
-    * **YOUR WRITING HERE**
+    * Gets the characters after index a (for "Test", if a = 2, then its substring will be "st")
 
   * `.substring(a, b)`
-    * **YOUR WRITING HERE**
+    * Gets the characters from index a up until index b, excludes b ("Macintosh" and a = 2, b = 5, substring will be "cin)
 
   * `.indexOf(str)`
-    * **YOUR WRITING HERE**
+    * Finds the character in a string ("pie" and str = e will be 2)
 
   * `.equals(str)`
-    * **YOUR WRITING HERE**
+    * Checks if the string is equivalent to itself ("hello" and "hi" will not be equal, but "a" and "a" will)
 
 
 2. *In your own words*, discuss what the following `for` loop accomplishes for `String s`:
@@ -21,4 +21,4 @@ for(int i = 0; i < s.length(); i++) {
       // DO STUFF
 }
 ```
-  * **YOUR WRITING HERE**
+  * Loops for the length of the string, if the length is 5, it will loop 5 times. This can be used for work on the string used for the loop