Merge Sort in Linked List

[kunal2504java]

There are a few minor issues in the code ig , Because the code throws some error while submitting on leetcode
I have written a code that works fine and follows the same approach as shown in the video
class Solution {
public ListNode sortList(ListNode head) {
if (head == null || head.next == null) {
return head;
}
// Find the middle of the list
ListNode mid = getMid(head);
ListNode left = sortList(head);
ListNode right = sortList(mid);
return merge(left, right);
}

ListNode merge(ListNode list1, ListNode list2) {
    ListNode dummyHead = new ListNode(); 
    ListNode tail = dummyHead; 

    while (list1 != null && list2 != null) {
        if (list1.val < list2.val) {
            tail.next = list1; 
            list1 = list1.next; 
        } else {
            tail.next = list2; 
            list2 = list2.next; 
        }
        tail = tail.next; 
    }

    tail.next = (list1 != null) ? list1 : list2;

    return dummyHead.next; 
}

ListNode getMid(ListNode head) {
    ListNode midPrev = null; 
    while (head != null && head.next != null) {
        midPrev = (midPrev == null) ? head : midPrev.next; // Move midPrev forward
        head = head.next.next; 
    }
    ListNode mid = midPrev.next;
    midPrev.next = null; 
    return mid;
}

}

[manikyarathore]

Workflow Failure Summary
The job failed mainly due to two issues:
Conda Configuration Error
CondaKeyError: 'channels': value 'defaults' not present in config

The workflow tries to remove or reference the defaults channel, but it’s not present. This doesn’t always break the job but should be handled safely.
Pre commit Hook Failures
Hooks like end-of-file-fixer, ruff-format, and ruff-linter failed due to formatting and linting issues.

Fixes

1. Safe Conda Channel Configuration
   Update the Conda setup step in .github/workflows/main.yaml to check before removing the defaults channel:

• name: Configure Conda
  run: |

  Only remove the defaults channel if it exists

  if conda config --show channels | grep defaults; then
  conda config --remove channels defaults
  else
  echo "defaults channel not present — skipping"
  fi

2. Fix Pre commit Hooks Locally
   Run the following to automatically apply all pre-commit fixes:
   pre-commit run --all-files
   git add .
   git commit -m "Fix pre-commit hook issues"

3. Fix Ruff Linting Errors
   After pre-commit, fix any remaining Ruff issues:
   ruff check . --fix
   git add .
   git commit -m "Fix Ruff lint issues"

Example of Code Formatting Fix :-

If the PR contains code like this for merging lists:

ListNode merge(ListNode list1, ListNode list2)
{
ListNode dummyHead = new ListNode();
ListNode tail = dummyHead;
while (list1 != null && list2 != null)
{
if (list1.val < list2.val)
{
tail.next = list1;
list1 = list1.next;
}
else
{
tail.next = list2;
list2 = list2.next;
}
tail = tail.next;
}

tail.next = (list1 != null) ? list1 : list2;
return dummyHead.next;

}

Ensure it’s properly formatted (matching your linter’s style rules) before committing.

Summary
Handle missing Conda channels safely
Run and commit pre commit fixes
Run ruff check . --fix
Push changes and re run the workflow
Once these are done, the pipeline should pass cleanly.