class 2

.gitignore

@@ -21,3 +21,5 @@
 
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
+
+launch.json

.vscode/launch.json

@@ -4,6 +4,27 @@
     // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
     "version": "0.2.0",
     "configurations": [
+        {
+            "type": "java",
+            "name": "CodeLens (Launch) - runRutabega",
+            "request": "launch",
+            "mainClass": "ClassProblems.Class3.runRutabega",
+            "projectName": "H212_e5d32889"
+        },
+        {
+            "type": "java",
+            "name": "CodeLens (Launch) - Rutabega",
+            "request": "launch",
+            "mainClass": "ClassProblems.Class3.Rutabega",
+            "projectName": "H212_e5d32889"
+        },
+        {
+            "type": "java",
+            "name": "CodeLens (Launch) - fib0",
+            "request": "launch",
+            "mainClass": "ClassProblems.Class3.fib0",
+            "projectName": "H212_e5d32889"
+        },
         {
             "type": "java",
             "name": "CodeLens (Launch) - E1_17",

ClassProblems/Class3/Rutabega.java

@@ -0,0 +1,18 @@
+package ClassProblems.Class3;
+
+import java.math.BigInteger;/**
+ * Rutabega
+ */
+public class Rutabega {
+
+    public static BigInteger fun(BigInteger index) {
+        return index.add(new BigInteger("1"));
+
+    }
+    public static void main(String[] args) {
+        BigInteger result = Rutabega.fun(new BigInteger("9223372036854775807"));
+        System.out.println(result);
+
+        // System.out.println(Rutabega.fun("1"));
+    }
+}

ClassProblems/Class3/fib0.java

@@ -0,0 +1,24 @@
+package ClassProblems.Class3;
+
+/**
+ * fib0
+ */
+public class fib0 {
+
+    private static long[] f = new long[92];
+
+    public static long fib(int n){
+        if (n == 0) 
+            return 0;
+        if (n == 1)
+            return 1;
+        if (f[n] > 0)
+            return f[n];
+
+        f[n] = fib(n-1) + fib(n-2);
+        return f[n];
+    }
+    public static void main(String[] args) {
+        System.out.println(fib(5));
+    }
+}

ClassProblems/Class3/runRutabega.java

@@ -0,0 +1,14 @@
+package ClassProblems.Class3;
+
+import java.math.BigInteger;
+
+/**
+ * runRutabega
+ */
+public class runRutabega {
+
+    public static void main(String[] args) {
+        BigInteger result = Rutabega.fun(new BigInteger("21421421"));
+        System.out.println(result);
+    }
+}

ClassProblems/Class3/whatever.java

@@ -0,0 +1,15 @@
+public class whatever{
+    // public static long fun(int index) {
+        // if (index == 1 ) return 1l;
+        // else if (index == 2) return 2l;
+        // else return fun(index-1) + fun(index-2);
+
+    public static long fun(int index, long a, long b) {    
+        if (index == 0 ) return b;
+        else return fun(index-1, b, a+b); //accumulated passing style
+        //homework01 using BigIntegers
+    }
+    public static void main(String[] args) {
+
+    }
+}

Homework/Homework01.java

@@ -0,0 +1,10 @@
+package Homework;
+import java.util.Dictionary;
+
+
+public class Homework01 {
+    Dictionary d = new Dictionary();
+    public static int fib(int n) {
+
+    }
+}

PrincetonJava/Booknotes/Chapter1.txt

@@ -62,5 +62,10 @@ Characters and Strings
         Double.parseDouble()
 
 Integers
-
+
+Methods - java programs are classes, its functions are Methods
+    static Methods
+        public static int fun(int index)
+    non-static Methods
+        public int fun(int index)