From 7a73162607544204032aa66cce755daf21edebda Mon Sep 17 00:00:00 2001
From: Matt Strapp <matt@mattstrapp.net>
Date: Tue, 24 May 2022 11:18:46 -0500
Subject: Graduate

Signed-off-by: Matt Strapp <matt@mattstrapp.net>
---
 csci1913/Java/project2_strap012.java | 148 +++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 csci1913/Java/project2_strap012.java

(limited to 'csci1913/Java/project2_strap012.java')

diff --git a/csci1913/Java/project2_strap012.java b/csci1913/Java/project2_strap012.java
new file mode 100644
index 0000000..3cbfa80
--- /dev/null
+++ b/csci1913/Java/project2_strap012.java
@@ -0,0 +1,148 @@
+//  SORT. Sort a linear singly-linked list of INTs.
+
+class Sort {
+
+    // NODE. A node in a linear singly linked list of INTs.
+
+    private static class Node {
+        private int number; // The INT in the node, duh.
+        private Node next; // The NODE that follows this one, or NULL.
+
+        // Constructor. Initialize a new NODE with NUMBER and NEXT.
+
+        private Node(int number, Node next) {
+            this.number = number;
+            this.next = next;
+        }
+    }
+
+    // MAKE NODES. Return a list of NODEs that contains INTs from NUMBERS in order
+    // of their appearance.
+
+    private static Node makeNodes(int... numbers) {
+        if (numbers.length > 0) {
+            Node first = new Node(numbers[0], null);
+            Node last = first;
+            for (int index = 1; index < numbers.length; index += 1) {
+                last.next = new Node(numbers[index], null);
+                last = last.next;
+            }
+            return first;
+        } else {
+            return null;
+        }
+    }
+
+    // WRITE NODES. Write the INTs from a list of NODEs in paired square brackets,
+    // separated by commas, with a newline at the end.
+
+    private static void writeNodes(Node nodes) {
+        System.out.print('[');
+        if (nodes != null) {
+            System.out.print(nodes.number);
+            nodes = nodes.next;
+            while (nodes != null) {
+                System.out.print(", ");
+                System.out.print(nodes.number);
+                nodes = nodes.next;
+            }
+        }
+        System.out.println(']');
+    }
+
+    // SORT NODES. Sort UNSORTED, a list of NODEs, into nondecreasing order of its
+    // NUMBER slots, without making new NODEs.
+
+    private static Node sortNodes(Node unsorted) {
+        Node left = null, right = null;
+        if (unsorted==null || unsorted.next==null) {
+        //unsorted is either empty or of length 1
+            return unsorted;
+        } 
+        //Halving phase
+        else {
+            int step = 1;
+            while (unsorted != null) {
+                Node next = unsorted.next;
+                if (step % 2 == 0) {    //Even case
+                    //Pops out first value and puts into Right
+                    unsorted.next = right;
+                    right = unsorted;
+                } else {                //Odd case
+                    // Pops out first value and puts into Left
+                    unsorted.next = left;
+                    left = unsorted; 
+                }
+                step++;
+                unsorted = next;
+            }
+        }
+        //Sorting (recursive) Phase
+        left = sortNodes(left);
+        right = sortNodes(right);
+
+        //Combining phase, variables needed for Q funs
+        Node end = null, temp = null, sorted = null;
+        //Special Initial Case
+        if (left.number < right.number) {
+            sorted = left; 
+            end = left;
+            temp = left.next;
+            left = temp;
+            end.next = null;
+        } else {
+            temp = right.next;
+            sorted = right;
+            end = right;
+            right = temp;
+            end.next = null;
+        }
+        //Loop for rearranging pointers. Easily the hardest part of the assignment
+        while (left != null && right != null) {
+            if (left.number < right.number) {
+                end.next = left;
+                end = left;
+                temp = left.next;
+                end.next = null;
+                left = temp;
+            } else { //Right is smaller or equal, put it at the end.
+                end.next = right;
+                end = right;
+                temp = right.next;
+                end.next = null;
+                right = temp;
+            }
+        } 
+
+        if (left == null) {
+            end.next=right;
+        } else if (right == null) {
+            end.next=left;
+        }
+        return sorted;
+    }
+
+    // MAIN. Run some examples. The comments show what must be printed.
+
+    public static void main(String[] args) {
+        writeNodes(sortNodes(makeNodes())); // []
+        writeNodes(sortNodes(makeNodes(1))); // [1]
+        writeNodes(sortNodes(makeNodes(1, 2))); // [1, 2]
+        writeNodes(sortNodes(makeNodes(2, 1))); // [1, 2]
+
+        writeNodes(sortNodes(makeNodes(1, 2, 3, 4, 5, 6, 7, 8, 9)));
+        // [1, 2, 3, 4, 5, 6, 7, 8, 9]
+
+        writeNodes(sortNodes(makeNodes(9, 8, 7, 6, 5, 4, 3, 2, 1)));
+        // [1, 2, 3, 4, 5, 6, 7, 8, 9]
+
+        writeNodes(sortNodes(makeNodes(3, 1, 4, 5, 9, 2, 6, 8, 7)));
+        // [1, 2, 3, 4, 5, 6, 7, 8, 9]
+
+        writeNodes(sortNodes(makeNodes(5,5,5,1,2,3,6,90,12,1,14)));
+        // [1, 1, 2, 3, 5, 5, 5, 6, 12, 14, 90]
+
+        writeNodes(sortNodes(makeNodes(1, 100, 6, 100, 1, 15, 10000, 12, 2, 0, -15)));
+        // [-15, 0, 1, 1, 2, 6, 12, 15, 100, 100, 10000]
+    }
+}
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