Added task 19.

Author: javadev

src/main/kotlin/com_github_leetcode/ListNode.kt

@@ -0,0 +1,34 @@
+package com_github_leetcode
+
+import java.util.Objects
+
+class ListNode {
+    var `val` = 0
+    var next: ListNode? = null
+
+    constructor() {}
+
+    constructor(`val`: Int) {
+        this.`val` = `val`
+    }
+
+    constructor(`val`: Int, next: ListNode?) {
+        this.`val` = `val`
+        this.next = next
+    }
+
+    override fun toString(): String {
+        val result = StringBuilder("" + `val`)
+        if (Objects.nonNull(next)) {
+            var current = next
+            while (current!!.next != null) {
+                result.append(", ")
+                result.append(current.`val`)
+                current = current.next
+            }
+            result.append(", ")
+            result.append(current.`val`)
+        }
+        return result.toString()
+    }
+}

src/main/kotlin/g0001_0100/s0002_add_two_numbers/ListNode.kt

@@ -1,5 +1,7 @@
 package g0001_0100.s0002_add_two_numbers
 
+import com_github_leetcode.ListNode
+
 /*
  * Definition for singly-linked list.
  * public class ListNode {

src/main/kotlin/g0001_0100/s0002_add_two_numbers/Solution.kt

@@ -0,0 +1,26 @@
+package g0001_0100.s0019_remove_nth_node_from_end_of_list
+
+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Two_Pointers #Linked_List
+
+import com_github_leetcode.ListNode
+
+class Solution {
+    var n = 0
+    fun removeNthFromEnd(head: ListNode?, n: Int): ListNode? {
+        this.n = n
+        val node = ListNode(0, head)
+        removeNth(node)
+        return node?.next
+    }
+
+    private fun removeNth(node: ListNode?) {
+        if (node?.next == null) {
+            return
+        }
+        removeNth(node.next)
+        n--
+        if (n == 0) {
+            node.next = node?.next?.next
+        }
+    }
+}

src/main/kotlin/g0001_0100/s0019_remove_nth_node_from_end_of_list/Solution.kt

@@ -0,0 +1,34 @@
+19\. Remove Nth Node From End of List
+
+Medium
+
+Given the `head` of a linked list, remove the `nth` node from the end of the list and return its head.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/10/03/remove_ex1.jpg)
+
+**Input:** head = [1,2,3,4,5], n = 2
+
+**Output:** [1,2,3,5]
+
+**Example 2:**
+
+**Input:** head = [1], n = 1
+
+**Output:** []
+
+**Example 3:**
+
+**Input:** head = [1,2], n = 1
+
+**Output:** [1]
+
+**Constraints:**
+
+*   The number of nodes in the list is `sz`.
+*   `1 <= sz <= 30`
+*   `0 <= Node.val <= 100`
+*   `1 <= n <= sz`
+
+**Follow up:** Could you do this in one pass?

src/main/kotlin/g0001_0100/s0019_remove_nth_node_from_end_of_list/readme.md

@@ -1,5 +1,6 @@
 package g0001_0100.s0002_add_two_numbers
 
+import com_github_leetcode.ListNode
 import org.hamcrest.CoreMatchers.equalTo
 import org.hamcrest.MatcherAssert.assertThat
 import org.junit.jupiter.api.Test

src/test/kotlin/g0001_0100/s0002_add_two_numbers/SolutionTest.kt

@@ -0,0 +1,29 @@
+package g0001_0100.s0019_remove_nth_node_from_end_of_list
+
+import com_github_leetcode.ListNode
+import org.hamcrest.CoreMatchers.equalTo
+import org.hamcrest.MatcherAssert.assertThat
+import org.junit.jupiter.api.Test
+
+internal class SolutionTest {
+    @Test
+    fun removeNthFromEnd() {
+        val head = ListNode()
+        val node1 = ListNode()
+        node1.`val` = 1
+        head.next = node1
+        val node2 = ListNode()
+        node2.`val` = 2
+        node1.next = node2
+        val node3 = ListNode()
+        node3.`val` = 3
+        node2.next = node3
+        val node4 = ListNode()
+        node4.`val` = 4
+        node3.next = node4
+        val node5 = ListNode()
+        node5.`val` = 5
+        node4.next = node5
+        assertThat(Solution().removeNthFromEnd(node1, 2).toString(), equalTo("1, 2, 3, 5"))
+    }
+}