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876: Middle of the Linked List

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`@@ -24,6 +24,7 @@ My solutions to LeetCode problems in Kotlin.`
`24`	`24`	`\| [412](https://leetcode.com/problems/fizz-buzz/) \| [Fizz Buzz](src/main/kotlin/com/schmoczer/leetcode/_0412/FizzBuzz.kt) \| Easy \|`
`25`	`25`	`\| [773](https://leetcode.com/problems/sliding-puzzle/) \| [Sliding Puzzle](src/main/kotlin/com/schmoczer/leetcode/_0773/SlidingPuzzle.kt) \| Hard \|`
`26`	`26`	`\| [796](https://leetcode.com/problems/rotate-string/) \| [Rotate String](src/main/kotlin/com/schmoczer/leetcode/_0796/RotateString.kt) \| Easy \|`
	`27`	`+\| [876](https://leetcode.com/problems/middle-of-the-linked-list/) \| [Middle of the Linked List](src/main/kotlin/com/schmoczer/leetcode/_0876/MiddleOfTheLinkedList.kt) \| Easy \|`
`27`	`28`	`\| [1342](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero/) \| [Number of Steps to Reduce a Number to Zero](src/main/kotlin/com/schmoczer/leetcode/_1342/NumberOfStepsToReduceANumberToZero.kt) \| Easy \|`
`28`	`29`	`\| [1480](https://leetcode.com/problems/running-sum-of-1d-array/) \| [Running Sum of 1d Array](src/main/kotlin/com/schmoczer/leetcode/_1480/RunningSumOf1dArray.kt) \| Easy \|`
`29`	`30`	`\| [1574](https://leetcode.com/problems/shortest-subarray-to-be-removed-to-make-array-sorted/) \| [Shortest Subarray to be Removed to Make Array Sorted](src/main/kotlin/com/schmoczer/leetcode/_1574/ShortestSubarray.kt) \| Medium \|`

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	`1`	`+package com.schmoczer.leetcode._0876`
	`2`	`+`
	`3`	`+class MiddleOfTheLinkedList {`
	`4`	`+ // Approach: use a fast and a slow pointer. Runtime 0ms Beats 100.00%`
	`5`	`+ fun middleNode(head: ListNode?): ListNode? {`
	`6`	`+ var current = head?.next`
	`7`	`+ var middle = head`
	`8`	`+ while (current != null) {`
	`9`	`+ current = current.next?.next`
	`10`	`+ middle = middle?.next`
	`11`	`+ }`
	`12`	`+ return middle`
	`13`	`+ }`
	`14`	`+}`
	`15`	`+`
	`16`	+class ListNode(var `val`: Int) {
	`17`	`+ var next: ListNode? = null`
	`18`	`+`
	`19`	+ constructor(`val`: Int, next: ListNode?) : this(`val`) {
	`20`	`+ this.next = next`
	`21`	`+ }`
	`22`	`+}`

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	`1`	`+# Middle of the Linked List`
	`2`	`+`
	`3`	+Given the `head` of a singly linked list, return the middle node of the linked list.
	`4`	`+`
	`5`	`+If there are two middle nodes, return the second middle node.`
	`6`	`+`
	`7`	`+Example 1:`
	`8`	`+`
	`9`	`+> Input: head = [1,2,3,4,5]`
	`10`	`+>`
	`11`	`+> Output: [3,4,5]`
	`12`	`+`
	`13`	`+Example 2:`
	`14`	`+`
	`15`	`+> Input: head = [1,2,3,4,5,6]`
	`16`	`+>`
	`17`	`+> Output: [4,5,6]`
	`18`	`+`
	`19`	`+Constraints:`
	`20`	`+`
	`21`	+- The number of nodes in the list is in the range `[1, 100]`.
	`22`	+- `1 <= Node.val <= 100`

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	`1`	`+package com.schmoczer.leetcode._0876`
	`2`	`+`
	`3`	`+import org.junit.jupiter.api.Assertions.assertEquals`
	`4`	`+import org.junit.jupiter.api.BeforeEach`
	`5`	`+import kotlin.test.Test`
	`6`	`+`
	`7`	`+class MiddleOfTheLinkedListTest {`
	`8`	`+ private lateinit var sut: MiddleOfTheLinkedList`
	`9`	`+`
	`10`	`+ @BeforeEach`
	`11`	`+ fun setUp() {`
	`12`	`+ sut = MiddleOfTheLinkedList()`
	`13`	`+ }`
	`14`	`+`
	`15`	`+ @Test`
	`16`	+ fun `middle of 1,2,3,4,5 is 3`() {
	`17`	`+ val input = createLinkedList(1, 2, 3, 4, 5)`
	`18`	`+ val expected = 3`
	`19`	`+`
	`20`	`+ val result = sut.middleNode(input)`
	`21`	`+`
	`22`	+ assertEquals(expected, result?.`val`)
	`23`	`+ }`
	`24`	`+`
	`25`	`+ @Test`
	`26`	+ fun `middle of 1,2,3,4,5,6 is 4`() {
	`27`	`+ val input = createLinkedList(1, 2, 3, 4, 5, 6)`
	`28`	`+ val expected = 4`
	`29`	`+`
	`30`	`+ val result = sut.middleNode(input)`
	`31`	`+`
	`32`	+ assertEquals(expected, result?.`val`)
	`33`	`+ }`
	`34`	`+`
	`35`	`+ private fun createLinkedList(vararg list: Int): ListNode {`
	`36`	`+ var node = ListNode(list.last())`
	`37`	`+ for (i in (0..<(list.size - 1)).reversed()) {`
	`38`	`+ node = ListNode(list[i], node)`
	`39`	`+ }`
	`40`	`+ return node`
	`41`	`+ }`
	`42`	`+}`

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