Process a linked list.

Author: jbey251

lesson_12/structs_java/structs_app/src/main/java/com/codedifferently/lesson12/Lesson12.java

@@ -2,11 +2,33 @@
 
 public class Lesson12 {
 
-  /**
-   * Provide the solution to LeetCode 3062 here:
-   * https://github.com/yang-su2000/Leetcode-algorithm-practice/tree/master/3062-winner-of-the-linked-list-game
-   */
   public String gameResult(ListNode head) {
-    return null;
+    int evenNumbers = 0;
+    int oddNumbers = 0;
+
+    ListNode current = head;
+
+    // While "current" does not strictly equal null & current.next does not strictly equal null, the
+    // current value is evenVariable, & oddVariable is the next value.
+    while (current != null && current.next != null) {
+      int evenVariable = current.val;
+      int oddVariable = current.next.val;
+
+      if (oddVariable > evenVariable) {
+        oddNumbers++;
+      } else if (evenVariable > oddVariable) {
+        evenNumbers++;
+      }
+
+      current = current.next.next;
+    }
+
+    if (oddNumbers > evenNumbers) {
+      return "Odd";
+    } else if (evenNumbers > oddNumbers) {
+      return "Even";
+    } else {
+      return "Tie";
+    }
   }
 }

lesson_12/structs_java/structs_app/src/main/java/com/codedifferently/lesson12/Stack.java

@@ -1,26 +1,45 @@
 package com.codedifferently.lesson12;
 
-/** Implement the below Stack by providing code for the class methods. */
 public class Stack {
   private ListNode top;
 
+  private static class ListNode {
+    int value;
+    ListNode next;
+
+    ListNode(int value) {
+      this.value = value;
+      this.next = null;
+    }
+  }
+
   public Stack() {
     this.top = null;
   }
 
   public void push(int value) {
-    // Your code here
+    ListNode newNode = new ListNode(value);
+    newNode.next = top;
+    top = newNode; // This will update top to the new node.
   }
 
   public int pop() {
-    return 0;
+    if (isEmpty()) {
+      throw new IllegalStateException("Stack is empty");
+    }
+    int poppedValue = top.value;
+    top = top.next;
+    return poppedValue;
   }
 
   public int peek() {
-    return 0;
+    if (isEmpty()) {
+      throw new IllegalStateException("Stack is empty");
+    }
+    return top.value;
   }
 
   public boolean isEmpty() {
-    return true;
+    return top == null;
   }
 }