add a solution for 1823

fishercoder1534 · fishercoder1534 · commit 84152b2e0c36 · 2021-10-26T16:16:03.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_1823.java b/src/main/java/com/fishercoder/solutions/_1823.java
@@ -1,6 +1,8 @@
 package com.fishercoder.solutions;
 
 import java.util.ArrayList;
+import java.util.Deque;
+import java.util.LinkedList;
 import java.util.List;
 
 public class _1823 {
@@ -19,4 +21,25 @@ public int findTheWinner(int n, int k) {
             return list.get(0);
         }
     }
+
+    public static class Solution2 {
+        /**
+         * My completely original solution: use a double linked list to keep moving people from
+         * the tail of the queue to the head of the queue until there's only one person in the queue who is the winner.
+         */
+        public int findTheWinner(int n, int k) {
+            Deque<Integer> doublyLinkedList = new LinkedList<>();
+            for (int i = 1; i <= n; i++) {
+                doublyLinkedList.addFirst(i);
+            }
+            while (doublyLinkedList.size() > 1) {
+                int counter = 1;
+                while (counter++ < k) {
+                    doublyLinkedList.addFirst(doublyLinkedList.pollLast());
+                }
+                doublyLinkedList.pollLast();
+            }
+            return doublyLinkedList.getLast();
+        }
+    }
 }
diff --git a/src/test/java/com/fishercoder/_1823Test.java b/src/test/java/com/fishercoder/_1823Test.java
@@ -0,0 +1,27 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1823;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1823Test {
+    private static _1823.Solution1 solution1;
+    private static _1823.Solution2 solution2;
+    private static int expected;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1823.Solution1();
+        solution2 = new _1823.Solution2();
+    }
+
+    @Test
+    public void test1() {
+        expected = 1;
+        assertEquals(expected, solution1.findTheWinner(6, 5));
+        assertEquals(expected, solution2.findTheWinner(6, 5));
+    }
+
+}
