add 876

Author: fishercoder1534

README.md

@@ -38,6 +38,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |900|[Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_900.java) | O(n) | O(1) | |Easy|
 |896|[Monotonic Array](https://leetcode.com/problems/monotonic-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_896.java) | O(n) | O(1) | |Easy|
 |884|[Uncommon Words from Two Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_884.java) | O(n) | O(k) | |Easy|
+|876|[Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_876.java) | O(n) | O(1) | |Easy|
 |867|[Transpose Matrix](https://leetcode.com/problems/transpose-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_867.java) | O(r*c) | O(r*c) | |Easy|
 |852|[Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_852.java) | O(n) | O(1) | |Easy|
 |844|[Backspace String Compare](https://leetcode.com/problems/backspace-string-compare/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_844.java) | O(n) | O(1) | |Easy|

src/main/java/com/fishercoder/solutions/_876.java

@@ -0,0 +1,42 @@
+package com.fishercoder.solutions;
+
+import com.fishercoder.common.classes.ListNode;
+
+/**
+ * 876. Middle of the Linked List
+ *
+ * Given a non-empty, singly linked list with head node head, return a middle node of linked list.
+ *
+ * If there are two middle nodes, return the second middle node.
+ *
+ * Example 1:
+ *
+ * Input: [1,2,3,4,5]
+ * Output: Node 3 from this list (Serialization: [3,4,5])
+ * The returned node has value 3.  (The judge's serialization of this node is [3,4,5]).
+ * Note that we returned a ListNode object ans, such that:
+ * ans.val = 3, ans.next.val = 4, ans.next.next.val = 5, and ans.next.next.next = NULL.
+ *
+ *  Example 2:
+ *
+ * Input: [1,2,3,4,5,6]
+ * Output: Node 4 from this list (Serialization: [4,5,6])
+ * Since the list has two middle nodes with values 3 and 4, we return the second one.
+ *
+ * Note:
+ *
+ * The number of nodes in the given list will be between 1 and 100.
+ */
+public class _876 {
+  public static class Solution1 {
+    public ListNode middleNode(ListNode head) {
+      ListNode fast = head;
+      ListNode slow = head;
+      while (fast != null && fast.next != null) {
+        fast = fast.next.next;
+        slow = slow.next;
+      }
+      return slow;
+    }
+  }
+}

src/test/java/com/fishercoder/_876Test.java

@@ -0,0 +1,35 @@
+package com.fishercoder;
+
+import com.fishercoder.common.classes.ListNode;
+import com.fishercoder.solutions._325;
+import com.fishercoder.solutions._876;
+import java.util.Arrays;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _876Test {
+  private static _876.Solution1 solution1;
+  private static ListNode head;
+  private static ListNode middle;
+
+  @BeforeClass
+  public static void setup() {
+    solution1 = new _876.Solution1();
+  }
+
+  @Test
+  public void test1() {
+    head = ListNode.createSinglyLinkedList(Arrays.asList(1, 2, 3, 4, 5));
+    middle = solution1.middleNode(head);
+    assertEquals(middle, ListNode.createSinglyLinkedList(Arrays.asList(3, 4, 5)));
+  }
+
+  @Test
+  public void test2() {
+    head = ListNode.createSinglyLinkedList(Arrays.asList(1, 2, 3, 4, 5, 6));
+    middle = solution1.middleNode(head);
+    assertEquals(middle, ListNode.createSinglyLinkedList(Arrays.asList(4, 5, 6)));
+  }
+}