solves partition list

Author: anishLearnsToCode

README.md

@@ -77,6 +77,7 @@
 |  81  | [Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii)                                                      |                                                          [![Java](assets/java.png)](src/SearchInRotatedSortedArrayII.java)                                                           |                                                                                                                                   |
 |  82  | [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii)                                              |                                                        [![Java](assets/java.png)](src/RemoveDuplicatesFromSortedListII.java)                                                         |                                                                                                                                   |
 |  83  | [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list)                                                    |                   [![Java](assets/java.png)](src/RemoveDuplicatesFromSortedList.java) [![Python](assets/python.png)](python/remove_duplicates_from_linked_list.py)                   |                                                                                                                                   |
+|  86  | [Partition List](https://leetcode.com/problems/partition-list)                                                                                            |                                                                  [![Java](assets/java.png)](src/PartitionList.java)                                                                  |                                                                                                                                   |
 |  88  | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array)                                                                                    |                                  [![Java](assets/java.png)](src/MergeSortedArray.java) [![Python](assets/python.png)](python/merge_sorted_array.py)                                  |                                                                                                                                   |
 |  94  | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)                                                             |                       [![Java](assets/java.png)](src/BinaryTreeInorderTraversal.java) [![Python](assets/python.png)](python/binary_tree_inorder_traversal.py)                        |                                                                                                                                   |
 | 100  | [Same Tree](https://leetcode.com/problems/same-tree)                                                                                                      |                                          [![Java](assets/java.png)](src/SameTree.java) [![Python](assets/python.png)](python/same_tree.py)                                           |                                                                                                                                   |

src/PartitionList.java

@@ -0,0 +1,29 @@
+// https://leetcode.com/problems/partition-list
+// T: O(N)
+// S: O(1)
+
+public class PartitionList {
+    public static class ListNode {
+        int val;
+        ListNode next;
+        ListNode() {}
+    }
+
+    public ListNode partition(ListNode head, int x) {
+        ListNode beforeHead = new ListNode(), beforeTemp = beforeHead;
+        ListNode afterHead = new ListNode(), afterTemp = afterHead;
+        while (head != null) {
+            if (head.val < x) {
+                beforeTemp.next = head;
+                beforeTemp = beforeTemp.next;
+            } else {
+                afterTemp.next = head;
+                afterTemp = afterTemp.next;
+            }
+            head = head.next;
+        }
+        afterTemp.next = null;
+        beforeTemp.next = afterHead.next;
+        return beforeHead.next;
+    }
+}