Added task 19.

Author: javadev

src/main/java/s0019.remove.nth.node.from.end.of.list/ListNode.java

@@ -0,0 +1,17 @@
+package s0019.remove.nth.node.from.end.of.list;
+
+public class ListNode {
+    int val;
+    ListNode next;
+
+    ListNode() {}
+
+    ListNode(int val) {
+        this.val = val;
+    }
+
+    ListNode(int val, ListNode next) {
+        this.val = val;
+        this.next = next;
+    }
+}

src/main/java/s0019.remove.nth.node.from.end.of.list/Solution.java

@@ -0,0 +1,25 @@
+package s0019.remove.nth.node.from.end.of.list;
+
+
+public class Solution {
+    int n;
+
+    public ListNode removeNthFromEnd(ListNode head, int n) {
+        this.n = n;
+        ListNode node = new ListNode(0, head);
+        removeNth(node);
+
+        return node.next;
+    }
+
+    private void removeNth(ListNode node) {
+        if (node.next == null) return;
+
+        removeNth(node.next);
+        this.n--;
+
+        if (this.n == 0) {
+            node.next = node.next.next;
+        }
+    }
+}

src/test/java/s0019.remove.nth.node.from.end.of.list/SolutionTest.java

@@ -0,0 +1,27 @@
+package s0019.remove.nth.node.from.end.of.list;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Test;
+
+public class SolutionTest {
+    @Test
+    public void fourSum() {
+        ListNode head = new ListNode();
+        head.val = 1;
+        ListNode node1 = new ListNode();
+        node1.val = 2;
+        head.next = node1;
+        ListNode node2 = new ListNode();
+        node2.val = 3;
+        node1.next = node2;
+        ListNode node3 = new ListNode();
+        node3.val = 4;
+        node2.next = node3;
+        ListNode node4 = new ListNode();
+        node4.val = 5;
+        node3.next = node4;
+        assertThat(new Solution().removeNthFromEnd(head, 2).toString(), equalTo("[1, 2, 3, 5]"));
+    }
+}