remove linked list elements

fishercoder1534 · fishercoder1534 · commit c44cb4d76f34 · 2016-08-05T10:01:16.000-07:00
diff --git a/EASY/src/easy/RemoveLinkedListElements.java b/EASY/src/easy/RemoveLinkedListElements.java
@@ -0,0 +1,45 @@
+package easy;
+
+import classes.ListNode;
+import utils.CommonUtils;
+
+/**203. Remove Linked List Elements  QuestionEditorial Solution  My Submissions
+Total Accepted: 74027
+Total Submissions: 249238
+Difficulty: Easy
+Remove all elements from a linked list of integers that have value val.
+
+Example
+Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
+Return: 1 --> 2 --> 3 --> 4 --> 5*/
+public class RemoveLinkedListElements {
+	/**This is a very good question to test your understanding of pointers/memory/addresses, although it's marked as EASY.
+	 * All the three nodes: dummy, curr and prev are indispensable.
+
+	 * 1. Eventually, we should return dummy.next as the final result.
+	 * 2. we assign head to curr, dummy to prev
+	 * 3. and then we use prev and curr to traverse through the list and do the work
+	 * 4. each time, we only move one node forward, so we don't need another while loop inside the while loop*/
+	public ListNode removeElements(ListNode head, int val) {
+		ListNode dummy = new ListNode(-1);
+		dummy.next = head;
+		ListNode curr = head, prev = dummy;
+		while(curr != null){
+			if(curr.val == val){
+				prev.next = curr.next;
+			} else {
+				prev = prev.next;
+			}
+			curr = curr.next;
+		}
+		return dummy.next;
+	}
+	
+	public static void main(String...strings){
+		RemoveLinkedListElements test = new RemoveLinkedListElements();
+		int val = 1;
+		ListNode head = new ListNode(1);
+		ListNode res = test.removeElements(head, val);
+		CommonUtils.printList(res);
+	}
+}
