Create Remove Nodes From Linked List.java

varunu28 · web-flow · commit cbe46171937d · 2022-11-27T17:45:33.000-08:00
diff --git a/Medium/Remove Nodes From Linked List.java b/Medium/Remove Nodes From Linked List.java
@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode removeNodes(ListNode head) {
+        ListNode revNode = reverse(head);
+        ListNode curr = revNode;
+        ListNode prev = null;
+        int maxValue = Integer.MIN_VALUE;
+        while (curr != null) {
+            if (curr.val < maxValue) {
+                prev.next = curr.next;
+            } else {
+                prev = curr;
+                maxValue = Math.max(curr.val, maxValue);
+            }
+            curr = curr.next;
+        }
+        return reverse(revNode);
+    }
+    
+    private ListNode reverse(ListNode node) {
+        ListNode curr = node;
+        ListNode prev = null;
+        while (curr != null) {
+            ListNode next = curr.next;
+            curr.next = prev;
+            prev = curr;
+            curr = next;
+        }
+        return prev;
+    }
+}
