Sync LeetCode submission Runtime - 3 ms (47.52%), Memory - 19.4 MB (65.84%)

Author: jimit105

1618-delete-n-nodes-after-m-nodes-of-a-linked-list/README.md

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+<p>You are given the <code>head</code> of a linked list and two integers <code>m</code> and <code>n</code>.</p>
+
+<p>Traverse the linked list and remove some nodes in the following way:</p>
+
+<ul>
+	<li>Start with the head as the current node.</li>
+	<li>Keep the first <code>m</code> nodes starting with the current node.</li>
+	<li>Remove the next <code>n</code> nodes</li>
+	<li>Keep repeating steps 2 and 3 until you reach the end of the list.</li>
+</ul>
+
+<p>Return <em>the head of the modified list after removing the mentioned nodes</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/06/06/sample_1_1848.png" style="width: 600px; height: 95px;" />
+<pre>
+<strong>Input:</strong> head = [1,2,3,4,5,6,7,8,9,10,11,12,13], m = 2, n = 3
+<strong>Output:</strong> [1,2,6,7,11,12]
+<strong>Explanation:</strong> Keep the first (m = 2) nodes starting from the head of the linked List  (1 -&gt;2) show in black nodes.
+Delete the next (n = 3) nodes (3 -&gt; 4 -&gt; 5) show in read nodes.
+Continue with the same procedure until reaching the tail of the Linked List.
+Head of the linked list after removing nodes is returned.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/06/06/sample_2_1848.png" style="width: 600px; height: 123px;" />
+<pre>
+<strong>Input:</strong> head = [1,2,3,4,5,6,7,8,9,10,11], m = 1, n = 3
+<strong>Output:</strong> [1,5,9]
+<strong>Explanation:</strong> Head of linked list after removing nodes is returned.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li>The number of nodes in the list is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
+	<li><code>1 &lt;= Node.val &lt;= 10<sup>6</sup></code></li>
+	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
+</ul>
+
+<p>&nbsp;</p>
+<p><strong>Follow up:</strong> Could you solve this problem by modifying the list in-place?</p>

1618-delete-n-nodes-after-m-nodes-of-a-linked-list/solution.py

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+# Approach 1: Traverse Linked List and Delete In Place
+
+# Time: O(n)
+# Space: O(1)
+
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def deleteNodes(self, head: Optional[ListNode], m: int, n: int) -> Optional[ListNode]:
+        current = head
+        last = head
+
+        while current:
+            m_count = m
+            n_count = n
+
+            while current and m_count != 0:
+                last = current
+                current = current.next
+                m_count -= 1
+
+            while current and n_count != 0:
+                current = current.next
+                n_count -= 1
+
+            last.next = current
+
+        return head
+