feat: adds Kimberlee's Lesson 12: Data Structures: Stacks, Queue, Linked Lists

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

@@ -1,12 +1,94 @@
 package com.codedifferently.lesson12;
 
+/* import java.util.LinkedList; */
+import java.util.ArrayList;
+/* import java.util.List; */
+import java.util.List;
+
 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;
+  /* class TeamNode {
+    int data;
+    TeamNode next;
+
+    public TeamNode(int data) {
+      this.data = data;
+      this.next = null;
+    }
+  }
+
+  class LinkedList {
+    TeamNode head;
+
+    public void add(int data) {
+      TeamNode newTeamNode = new TeamNode(data);
+      if (head == null) {
+        head = newTeamNode;
+      } else {
+        TeamNode temp = head;
+        while (temp.next != null) {
+          temp = temp.next;
+        }
+        temp.next = newTeamNode;
+      }
+    } */
+
+    public String gameResult(/* Team */ListNode head) {
+      List<String> result = new ArrayList<>();
+      int evenCounter = 0;
+      int oddCounter = 0;
+      /* Team */ListNode current = head;
+
+      while (current != null && current.next != null) {
+        int evenValue = current.data;
+        int oddValue = current.next.data;
+
+        if (evenValue > oddValue) {
+          result.add("even");
+          evenCounter++;
+        } else {
+          result.add("odd");
+          oddCounter++;
+        }
+
+        current = current.next.next;
+      }
+
+      String winningTeam;
+      if (evenCounter > oddCounter) {
+        winningTeam = "even";
+      } else if (oddCounter > evenCounter) {
+        winningTeam = "odd";
+      } else {
+        winningTeam = "tie";
+      }
+
+      System.out.println("Node team with higher value in each pair: " + result);
+      System.out.println("The team with the most high-values is: " + winningTeam);
+
+      return winningTeam;
+    }
+  }
+
+
+/* public class Main {
+  public static void main(String[] args) {
+    LinkedList list = new LinkedList();
+
+    list.add(2);
+    list.add(5);
+    list.add(4);
+    list.add(7);
+    list.add(20);
+    list.add(5);
+
+    String winningTeam = list.gameResult(list.head);
+
+    System.out.println("Team with most high-value pairs: " + winningTeam);
   }
 }
+} */

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

@@ -14,4 +14,39 @@ public class ListNode {
     this.val = val;
     this.next = next;
   }
+
+
+/* public static String listWinner(ListNode head) {
+  int evenScore = 0;
+  int oddScore = 0;
+
+  ListNode current = head;
+  while (current != null && current.next != null) {
+    int evenVal = current.val;
+    int oddVal = current.next.val;
+
+    if (evenVal > oddVal) {
+      evenScore++;
+    } else if (oddVal > evenVal) {
+      oddScore++;
+    }
+
+    current = current.next.next;
+    }
+
+  if (evenScore > oddScore) {
+    return "Even";
+  } else if (oddScore > evenScore) {
+    return "Odd";
+  } else {
+    return "Tie";
+  }
 }
+
+public static void main(String[] args) {
+  ListNode head = new ListNode(2, new ListNode(5, new ListNode(4, new ListNode(7, new ListNode(20, new ListNode(5))))));
+
+  String winner = listWinner(head);
+  System.out.println("The winner is: " + winner);
+} */
+} 

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

@@ -10,17 +10,29 @@ public Stack() {
 
   public void push(int value) {
     // Your code here
+    ListNode newNode = ListNode(value);
+    newNode.next = top;  
+    top = newNode;  
   }
 
   public int pop() {
-    return 0;
+    if (isEmpty()) {
+      throw new RuntimeException("Stack is empty! Cannot pop.");
+    }
+    int value = top.val;  
+    top = top.next;  
+    return value;   
   }
 
   public int peek() {
-    return 0;
+    if (isEmpty()) {
+      throw new RuntimeException("Stack is empty! Cannot peek.");
+    }
+    return top.val;  
   }
-
+  
   public boolean isEmpty() {
-    return true;
+    return top == null;  
   }
 }
+