2024-09-06 Daily Challenge

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Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 6

Description

Delete Nodes From Linked List Present in Array

You are given an array of integers nums and the head of a linked list. Return the head of the modified linked list after removing all nodes from the linked list that have a value that exists in nums.

 

Example 1:

Input: nums = [1,2,3], head = [1,2,3,4,5]

Output: [4,5]

Explanation:

Remove the nodes with values 1, 2, and 3.

Example 2:

Input: nums = [1], head = [1,2,1,2,1,2]

Output: [2,2,2]

Explanation:

Remove the nodes with value 1.

Example 3:

Input: nums = [5], head = [1,2,3,4]

Output: [1,2,3,4]

Explanation:

No node has value 5.

 

Constraints:

  • 1 <= nums.length <= 105
  • 1 <= nums[i] <= 105
  • All elements in nums are unique.
  • The number of nodes in the given list is in the range [1, 105].
  • 1 <= Node.val <= 105
  • The input is generated such that there is at least one node in the linked list that has a value not present in nums.

Solution

class Solution {
public:
  ListNode* modifiedList(vector<int>& nums, ListNode* head) {
    set<int> num(nums.begin(), nums.end());

    ListNode *newHead = new ListNode();
    ListNode *current = newHead;
    while(head) {
      if(!num.count(head->val)) {
        current->next = head;
        current = current->next;
      }
      head = head->next;
    }
    current->next = nullptr;
    return newHead->next;
  }
};
Algorithm