feat: add lesson12 HW & Extra credit

Author: DavisD251

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

@@ -1,5 +1,7 @@
 package com.codedifferently.lesson12;
 
+import java.util.EmptyStackException;
+
 /** Implement the below Stack by providing code for the class methods. */
 public class Stack {
   private ListNode top;
@@ -9,18 +11,30 @@ public Stack() {
   }
 
   public void push(int value) {
-    // Your code here
+    ListNode newNode = new ListNode(value);
+    newNode.next = top;
+    top = newNode;
   }
 
   public int pop() {
-    return 0;
+    if (top == null) {
+      throw new EmptyStackException();
+    }
+    int poppedval = top.val;
+    top = top.next;
+    return poppedval;
   }
 
   public int peek() {
-    return 0;
+    if (top == null) {
+      throw new EmptyStackException();
+    }
+    return top.val;
   }
 
   public boolean isEmpty() {
-    return true;
+    if (top == null) {
+      return true;
+    } else return false;
   }
 }

lesson_12/structs_ts/src/lesson12.ts

@@ -6,6 +6,28 @@ export class Lesson12 {
    * https://github.com/yang-su2000/Leetcode-algorithm-practice/tree/master/3062-winner-of-the-linked-list-game
    */
   public gameResult(head: ListNode | null): string {
-    return '';
+    const ls: number[] = [0, 0]; //Sets list to only represent numbers
+    while (head && head.next) {
+      //Goes through linked list until there are no more numbers
+      if (head.val !== head.next.val && head.val % 2 === 0) {
+        //determines if we have different numbers as well as if head number is divisible by 2
+        if (head.val > head.next.val) {
+          //Checks if the number was even and is greater than second number
+          ls[head.val % 2] += 1; //If both were true this function occurs and gives even a point
+        } else {
+          ls[head.next.val % 2] += 1; //If either are false then give odd a point
+        }
+      }
+      head = head.next; //Proceed to next node/set of numbers to continue unil we are out of pairs
+    }
+
+    if (ls[0] > ls[1]) {
+      //Tells us the result based on which list[] got the point vvv
+      return 'Even';
+    } else if (ls[0] === ls[1]) {
+      return 'Tie';
+    } else {
+      return 'Odd';
+    }
   }
 }

lesson_12/structs_ts/src/stack.ts

@@ -8,18 +8,32 @@ export class Stack {
   }
 
   push(value: number): void {
-    throw new Error('Not implemented');
+    const newNode = new ListNode(value);
+    newNode.next = this.top;
+    this.top = newNode;
   }
 
   pop(): number | undefined {
-    throw new Error('Not implemented');
+    if (this.top === undefined) {
+      return undefined;
+    }
+    const poppedValue = this.top.val;
+    this.top = this.top.next;
+    return poppedValue;
   }
 
   peek(): number | null {
-    throw new Error('Not implemented');
+    if (this.top === undefined) {
+      throw new Error('Stack is empty');
+    }
+    return this.top.val;
   }
 
   isEmpty(): boolean {
-    throw new Error('Not implemented');
+    if (this.top === undefined) {
+      return true;
+    } else {
+      return false;
+    }
   }
 }