Dav

src/main/java/Lecture4Exercises.java

@@ -1,11 +1,21 @@
+import java.lang.reflect.Array;
+import java.util.Locale;
+
 public class Lecture4Exercises {
 
     /*
      *   implement a function that returns factorial of given n
      *   lecture 4 page 15
      */
     public long factorial(int n) {
-        return 0L;
+        int ans = 1,i=n;
+
+        while (i!=0){
+            ans*=i;
+            i--;
+        }
+
+        return ans;
     }
 
     /*
@@ -14,15 +24,35 @@ public long factorial(int n) {
      *   lecture 4 page 19
      */
     public long fibonacci(int n) {
-        return 0;
+        Long a= Long.valueOf(1),b= Long.valueOf(1),i= Long.valueOf(2);
+
+        while(i<n){
+            a+=b;
+            b+=a;
+            i+=2;
+        }
+
+        if(i==n){
+            return b;
+        }
+
+        else{
+            return a;
+        }
     }
 
     /*
      *   implement a function that return reverse of a given word
      *   lecture 4 page 19
      */
     public String reverse(String word) {
-        return null;
+        String reversed="";
+
+        for (int i=word.length()-1;i>=0;i--){
+            reversed = reversed + word.charAt(i);
+        }
+
+        return reversed;
     }
 
     /*
@@ -32,7 +62,10 @@ public String reverse(String word) {
      *   lecture 4 page 19
      */
     public boolean isPalindrome(String line) {
-        return false;
+        String line1 = line;
+        line1 = line1.replaceAll("\\s", "");
+        line1 = line1.toLowerCase(Locale.ROOT);
+        return reverse(line1).equals(line1);
     }
 
     /*
@@ -47,6 +80,18 @@ public boolean isPalindrome(String line) {
      *   lecture 4 page 26
      */
     public char[][] dotPlot(String str1, String str2) {
-        return null;
+        char [][] ans = new char[str1.length()][str2.length()];
+        for (int i=0;i<str1.length();i++){
+            for (int j=0;j<str2.length();j++){
+                if (str1.charAt(i)==str2.charAt(j)){
+                    ans[i][j]='*';
+                }
+                else{
+                    ans[i][j]=' ';
+                }
+            }
+        }
+
+        return ans;
     }
 }

src/main/java/Lecture5Exercises.java

@@ -1,3 +1,6 @@
+import java.util.ArrayList;
+import java.util.Random;
+
 public class Lecture5Exercises {
 
     /*
@@ -6,7 +9,11 @@ public class Lecture5Exercises {
      *   lecture 5 page 14
      */
     public String weakPassword(int length) {
-        return null;
+        String password = "";
+        for (int i = 0; i < length; i++) {
+            password = password + (char) randomNum(97, 122);
+        }
+        return password;
     }
 
     /*
@@ -15,7 +22,26 @@ public String weakPassword(int length) {
      *   lecture 5 page 14
      */
     public String strongPassword(int length) throws Exception {
-        return null;
+        String password;
+        ArrayList <Character> opts = new ArrayList<>();
+        optMaker(opts);
+
+        while (true) {
+            password = "";
+
+
+            for (int i = 0; i < length; i++) {
+                password = password + opts.get(randomNum(0, opts.size() - 1));
+            }
+
+            System.out.println(password);
+
+            String par ="([a-z]+)(\\d+)([+*?^$(){}&|]+)";
+
+            if (password.matches(par)){
+                return password;
+            }
+        }
     }
 
     /*
@@ -27,6 +53,71 @@ public String strongPassword(int length) throws Exception {
      *   lecture 5 page 17
      */
     public boolean isFiboBin(int n) {
-        return false;
+        int i=0;
+        while (fibonacci(i) + binSum(i) < n){
+            i++;
+        }
+
+        return fibonacci(i) + binSum(i) == n;
+    }
+
+    public int randomNum(int a, int b) {
+        Random r = new Random();
+        int result = r.nextInt(b - a + 1) + a;
+        return result;
+    }
+
+
+
+    static int binSum(int n) {
+        int[] binaryNum = new int[1000];
+
+        int i = 0;
+        while (n > 0) {
+            binaryNum[i] = n % 2;
+            n = n / 2;
+            i++;
+        }
+
+        int sum = 0;
+        for (int value : binaryNum) {
+            sum += value;
+        }
+
+        return sum;
+    }
+
+    public long fibonacci(int n) {
+        Long a= Long.valueOf(1),b= Long.valueOf(1),i= Long.valueOf(2);
+
+        while(i<n){
+            a+=b;
+            b+=a;
+            i+=2;
+        }
+
+        if(i==n){
+            return b;
+        }
+
+        else{
+            return a;
+        }
+    }
+
+    public static void optMaker(ArrayList<Character> opts){
+        for(int i=48;i<58;i++){
+            opts.add((char) i);
+        }
+
+        for(int i=97;i<123;i++){
+            opts.add((char) i);
+        }
+
+        String specials = ".+*?^$(){}|";
+
+        for (int i=0;i<specials.length();i++){
+            opts.add(specials.charAt(i));
+        }
     }
 }

src/main/java/Lecture6Exercises.java

@@ -1,3 +1,5 @@
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 public class Lecture6Exercises {
@@ -8,7 +10,12 @@ public class Lecture6Exercises {
      *   lecture 6 page  16
      */
     public long calculateEvenSum(int[] arr) {
-        return 0L;
+        long sum=0;
+        for(int i=0;i<arr.length;){
+            sum+=arr[i];
+            i+=2;
+        }
+        return sum;
     }
 
     /*
@@ -17,15 +24,33 @@ public long calculateEvenSum(int[] arr) {
      *   lecture 6 page 16
      */
     public int[] reverseArray(int[] arr) {
-        return null;
+        int[] reversed = new int[arr.length];
+        int j=0;
+        for(int i=arr.length - 1;i>=0;i--){
+            reversed[j]=arr[i];
+            j++;
+        }
+        return reversed;
     }
 
     /*
      *   implement a function that calculate product of two 2-dim matrices
      *   lecture 6 page 21
      */
     public double[][] matrixProduct(double[][] m1, double[][] m2) throws RuntimeException {
-        return null;
+        int row = m1.length;
+        int coloumn_row = m1[0].length;
+        int coloumn = m2[0].length;
+        double[][] r = new double[row][coloumn];
+        for (int i=0;i<row;i++){
+            for(int j=0;j<coloumn;j++){
+                r[i][j]=0;
+                for(int k=0;k<coloumn_row;k++){
+                    r[i][j]+=m1[i][k]*m2[k][j];
+                }
+            }
+        }
+        return r;
     }
 
     /*
@@ -34,7 +59,11 @@ public double[][] matrixProduct(double[][] m1, double[][] m2) throws RuntimeExce
      *   lecture 6 page 30
      */
     public List<List<String>> arrayToList(String[][] names) {
-        return null;
+        List<List<String>> ans = new ArrayList<>();
+        for (int i=0;i< names.length;i++){
+            ans.add(new ArrayList<String>(List.of(names[i])));
+        }
+        return ans;
     }
 
     /*
@@ -43,14 +72,39 @@ public List<List<String>> arrayToList(String[][] names) {
      *   lecture 6 page 30
      */
     public List<Integer> primeFactors(int n) {
-        return null;
+        List<Integer> primes = new ArrayList<Integer>();
+        for (int i=2;i<=n;i++){
+            if (isPrime(i)){
+                if (n%i==0){
+                    primes.add(i);
+                }
+            }
+        }
+
+        return primes;
     }
 
     /*
      *   implement a function that return a list of words in a given string
      *   lecture 6 page 30
      */
     public List<String> extractWord(String line) {
-        return null;
+        line = line.replaceAll("[$&+,:;=?@#|'<>.-^*()%!]" , "");
+        List<String> myList = new ArrayList<String>(Arrays.asList(line.split(" ")));
+        return myList;
+    }
+
+    public boolean isPrime(int num)
+    {
+        if(num<=1)
+        {
+            return false;
+        }
+        for(int i=2;i<=num/2;i++)
+        {
+            if((num%i)==0)
+                return  false;
+        }
+        return true;
     }
 }