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Semester 2/Programming 2/Week 10 Revision/Q1.md

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+File Input / Output

Semester 2/Programming 2/Week 10 Revision/Q3.md

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+Recursion via factorial function
+```java
+int fact(int n)
+    {
+	    int result;
+	    if(n==0 || n==1)
+		    return 1;
+
+       result = fact(n-1) * n;
+       return result;
+    }
+```
+Since factorial(0) or factorial(1) is just 1, we return 1 in these scenarios
+If we have factorial(2), we would do factorial(1)\*2 = 2
+fact(5) = factorial(4) \* 5 = 5\*4\*3\*2\*1 = 120

Semester 2/Programming 2/Week 10 Revision/Q4.md

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+```java
+public class IntNode
+{
+public int info;
+public IntNode next;
+}
+```
+![](Pasted%20image%2020240319224232.png)
+a) Write code to add 50 to the appropriate field of the node pointed to by temp.
+
+```java
+temp.info += 50;
+```
+
+b) Write code to remove from the list the item after temp.
+```java
+temp.next = temp.next.next;
+```
+
+c) Write the code to remove from the list temp.
+```java
+temp.info = temp.next.info; // Assign the next node's value to temp - this will overwrite temp's value.
+temp.next = temp.next.next; // Set the pointer for temp's next node to the node after the value taken for temp - this effectively clones temp.next and replaces temp.
+```
+
+d) Write code to go through the list and to sum all the values within the list. You may assume the existence of head, a reference to the start of the list.
+
+```java
+IntNode current = head;
+int sum = 0;
+while ( current != null ) {
+	sum += current.info;
+	current = current.next;
+}
+```

Semester 2/Programming 2/Week 10 Revision/Q5.md

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+a) List the order in which the nodes are visited in: 
+post-order.
+![](Pasted%20image%2020240319225420.png)
+D,B,F,G,E,C,A
+
+pre-order
+A,B,D,C,E,F,G
+
+in-order
+D,B,F,E,G,C,A
+
+b)
+```java
+public class BinTreeNode
+{
+	public String info;
+	public BinTreeNode leftChild, rightChild;
+}
+```
+
+```java
+public void postTraverse( BinTreeNode node )
+{
+	if ( node != null )
+	{
+		postTraverse( node.leftNode );
+		postTraverse( node.rightNode );
+		System.out.println( node.info );
+	}
+}
+```
+
+c) The following method counts the number of nodes in the tree
+```java
+public int countTree(BinTreeNode t)
+{
+	int count;
+	if (t == null)
+		count = 0
+	else
+		count = countTree(t.leftChild)+countTree(t.rightChild)+1;
+	return count;
+}
+```
+![](Pasted%20image%2020240319234142.png)
+
+countTree(root)
+-> count = countTree(t.leftChild) + countTree(t.rightChild+1)
+countTree(t.leftChild)
+-> return 1, since left and right child null
+countTree(t.rightChild)
+-> return 1, since left and right child null
+count = 1 + 1 + 1 = 3