83. Remove Duplicates from Sorted List (#35)

* 83. Remove Duplicates from Sorted List * Fix formatting
xtenzQ · Jul 26, 2024 · 6e71704 · 6e71704
1 parent 18cdf85
commit 6e71704
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diff --git a/algorithms-and-data-structures/src/main/java/com/xtenzq/linkedlist/FastPointers.java b/algorithms-and-data-structures/src/main/java/com/xtenzq/linkedlist/FastPointers.java
@@ -81,4 +81,24 @@ public static ListNode middleNode(ListNode head) {
 
         return slow;
     }
+
+    /**
+     * Deletes all duplicates such that each element appears only once
+     *
+     * @param head head of linked list
+     * @return linked list with unique elements
+     * @implNote This method runs in {@code O(n)} time complexity and {@code O(1)} space complexity
+     * @see <a href="https://leetcode.com/problems/remove-duplicates-from-sorted-list/">83. Remove Duplicates from Sorted List</a>
+     */
+    public static ListNode deleteDuplicates(ListNode head) {
+        ListNode pointer = head;
+        while (pointer != null && pointer.next != null) {
+            if (pointer.val == pointer.next.val) {
+                pointer.next = pointer.next.next;
+            } else {
+                pointer = pointer.next;
+            }
+        }
+        return head;
+    }
 }
diff --git a/algorithms-and-data-structures/src/test/java/com/xtenzq/linkedlist/FastPointersTest.java b/algorithms-and-data-structures/src/test/java/com/xtenzq/linkedlist/FastPointersTest.java
@@ -2,6 +2,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import static com.xtenzq.linkedlist.FastPointers.deleteDuplicates;
 import static com.xtenzq.linkedlist.FastPointers.getMiddle;
 import static com.xtenzq.linkedlist.FastPointers.hasCycle;
 import static com.xtenzq.linkedlist.FastPointers.middleNode;
@@ -60,4 +61,19 @@ void middleNode_case1() {
     void middleNode_case2() {
         assertEquals(buildLinkedList(4, 5, 6), middleNode(buildLinkedList(1,2,3,4,5,6)));
     }
+
+    @Test
+    void deleteDuplicates_case1() {
+        assertEquals(buildLinkedList(1, 2, 3, 4, 5), deleteDuplicates(buildLinkedList(1, 2, 3, 3, 4, 4, 5)));
+    }
+
+    @Test
+    void deleteDuplicates_case2() {
+        assertEquals(buildLinkedList(1), deleteDuplicates(buildLinkedList(1)));
+    }
+
+    @Test
+    void deleteDuplicates_case3() {
+        assertEquals(buildLinkedList(1), deleteDuplicates(buildLinkedList(1, 1, 1)));
+    }
 }