java: add «237. Delete Node in a Linked List»

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/delete-node-in-a-linked-list.java

@@ -0,0 +1,21 @@
+/**
+ * Definition for singly-linked list. public class ListNode { int val; ListNode next; ListNode(int
+ * x) { val = x; } }
+ */
+class Solution {
+  private boolean isLastNode(ListNode node) {
+    return node != null && node.next == null;
+  }
+
+  public void deleteNode(ListNode node) {
+    while (node != null) {
+      node.val = node.next.val;
+
+      if (isLastNode(node.next)) {
+        node.next = null;
+      }
+
+      node = node.next;
+    }
+  }
+}