Merge branch 'main' of https://github.com/abckhush/codeharborhub.github.io

Author: abckhush

.github/workflows/greetings.yml

@@ -1,20 +1,61 @@
-name: Greetings
+name: 'Greetings'
 
-on: [pull_request_target, issues]
+on:
+  issues:
+    types: [opened]
+  pull_request_target:
+    types: [opened]
+
+permissions:
+  issues: write
+  pull-requests: write
 
 jobs:
-  greeting:
+  welcome:
     runs-on: ubuntu-latest
-    permissions:
-      issues: write
-      pull-requests: write
+
     steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
       - name: Greet first-time contributors
         id: greet
         uses: actions/first-interaction@v1
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           issue-message: |
-            Hi there! 👋 Thank you for opening your first issue on CodeHarborHub. We're excited to hear your thoughts and help you out. Please provide as much detail as you can so we can assist you effectively.
+            Hi there! 👋 Thank you for opening your issue on CodeHarborHub. We're excited to hear your thoughts and help you out. You've raised a great topic! Please provide as much detail as you can so we can assist you effectively. Welcome aboard!
           pr-message: |
-            Hi there! 👋 Thank you for submitting your first pull request to CodeHarborHub. We appreciate your contribution! Our team will review it soon. If you have any questions or need further assistance, feel free to reach out.
+            Hi there! 👋 Thank you for submitting your pull request to CodeHarborHub. Great job on the contribution! 🎉 We appreciate your efforts and our team will review it soon. If you have any questions or need further assistance, feel free to reach out. Keep up the great work!
+
+      - name: Assign issue or pull request to team member
+        if: github.event_name == 'issues' || github.event_name == 'pull_request_target'
+        run: |
+          ISSUE_NUMBER=${{ github.event.issue.number || github.event.pull_request.number }}
+          curl -X POST -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
+          -d '{"assignees":["team-member"]}' \
+          "https://api.github.com/repos/${{ github.repository }}/issues/${ISSUE_NUMBER}"
+
+      - name: Welcome message for community contributors
+        if: github.event_name == 'issues' || github.event_name == 'pull_request_target'
+        uses: EddieHubCommunity/gh-action-community/src/welcome@main
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          issue-message: "Hi @${{ github.actor }}! Thanks for opening this issue. We appreciate your contribution to this open-source project. Your input is valuable and we aim to respond or assign your issue as soon as possible. Thanks again!"
+          pr-message: "Great job, @${{ github.actor }}! 🎉 Thank you for submitting your pull request to CodeHarborHub. We appreciate your contribution and enthusiasm! Our team will review it soon. If you have any questions or need further assistance, feel free to reach out. Thanks for contributing!"
+
+      - name: Label first-time issues
+        if: github.event_name == 'issues'
+        run: |
+          ISSUE_NUMBER=${{ github.event.issue.number }}
+          curl -X POST -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
+          -d '{"labels":["CodeHarborHub - Thanks for creating an issue!"]}' \
+          "https://api.github.com/repos/${{ github.repository }}/issues/${ISSUE_NUMBER}"
+
+      - name: Label first-time pull requests
+        if: github.event_name == 'pull_request_target'
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          curl -X POST -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
+          -d '{"labels":["CodeHarborHub - Thanks for creating a pull request!"]}' \
+          "https://api.github.com/repos/${{ github.repository }}/issues/${PR_NUMBER}"

dsa-problems/leetcode-problems/0200-0299.md

@@ -38,7 +38,7 @@ export const problems = [
         "problemName": "204. Count Primes",
         "difficulty": "Medium",
         "leetCodeLink": "https://leetcode.com/problems/count-primes",
-        "solutionLink": "#"
+        "solutionLink": "/dsa-solutions/lc-solutions/0200-0299/count-primes"
     },
     {
         "problemName": "205. Isomorphic Strings",

dsa-problems/leetcode-problems/0400-0499.md

@@ -194,7 +194,7 @@ export const problems = [
     "problemName": "430. Flatten a Multilevel Doubly Linked List",
     "difficulty": "Medium",
     "leetCodeLink": "https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list",
-    "solutionLink": "#"
+    "solutionLink": "/dsa-solutions/lc-solutions/0400-0499/flatten-a-multilevel-doubly-linked-list"
   },
   {
     "problemName": "431. Encode N-ary Tree to Binary Tree",

dsa-solutions/lc-solutions/0000-0099/0018-4Sum.md

@@ -5,13 +5,14 @@ sidebar_label: 0018-FourSum
 tags:
   - Two Pointers
 description: "Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]]"
+
 ---
 
 ## Problem Description
 
 | Problem Statement                                       | Solution Link                                                              | LeetCode Profile                                        |
 | :------------------------------------------------------ | :------------------------------------------------------------------------- | :------------------------------------------------------ |
-| [4Sum](https://leetcode.com/problems/4sum/description/) | [4Sum Solution on LeetCode](https://leetcode.com/problems/4sum/solutions/) | [Abhinash Singh](https://leetcode.com/u/singhabhinash/) |
+| [4Sum](https://leetcode.com/problems/4sum/description/) | [4Sum Solution on LeetCode](https://leetcode.com/problems/4sum/solutions/) | [Nikita Saini](https://leetcode.com/u/Saini_Nikita/) |
 
 ### Problem Description
 
@@ -26,12 +27,10 @@ You may return the answer in any order.
 ### Examples
 
 #### Example 1
-
 - **Input:** `nums = [1,0,-1,0,-2,2], target = 0`
 - **Output:** `[[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]`
 
 #### Example 2
-
 - **Input:** `nums = [2,2,2,2,2], target = 8`
 - **Output:** `[[2,2,2,2]]`
 
@@ -57,7 +56,6 @@ To solve the problem, we can use the following approach:
 10: Skip duplicate values of left and right pointers to avoid duplicate quadruplets.
 11: Return the result.
 
-
 ### Solution Code
 
 #### Python
@@ -87,14 +85,27 @@ class Solution(object):
                         right -= 1
                     else:
                         quadruplets.append([nums[i], nums[j], nums[left], nums[right]])
-                        # Skip duplicates
                         while left < right and nums[left] == nums[left + 1]:
                             left += 1
                         while left < right and nums[right] == nums[right - 1]:
                             right -= 1
                         left += 1
                         right -= 1
-        return quadruplets
+        return result
+
+                        while left < right and nums[left] == nums[left + 1]:
+                            left += 1
+                        while left < right and nums[right] == nums[right - 1]:
+                            right -= 1
+
+                        left += 1
+                        right -= 1
+                    elif sum_ < target:
+                        left += 1
+                    else:
+                        right -= 1
+
+        return result
 ```
 
 #### C++
@@ -233,3 +244,23 @@ var fourSum = function(nums, target) {
 ### Conclusion
 
 The given solution sorts the input list and uses a nested loop structure with two pointers to find all unique quadruplets that sum up to the target. By using a set to store the quadruplets, it ensures that duplicates are avoided. The solution efficiently narrows down potential combinations by adjusting the pointers based on the current sum relative to the target. This approach is effective for generating the required output while maintaining uniqueness.
+
+## Step-by-Step Algorithm
+
+1. **Input Validation**: Check if the array is null or has fewer than 4 elements. If so, return an empty list.
+2. **Sort the Array**: Sort the input array `nums`.
+3. **Outer Loop**: Iterate over the array with index `i` from `0` to `n-4`.
+   - Skip duplicate elements by checking if `nums[i] == nums[i-1]` (for `i > 0`).
+4. **Inner Loop**: For each `i`, iterate with index `j` from `i+1` to `n-3`.
+   - Skip duplicate elements by checking if `nums[j] == nums[j-1]` (for `j > i+1`).
+5. **Two Pointers**: Initialize two pointers `left = j+1` and `right = n-1`.
+6. **Finding Quadruplets**:
+   - While `left < right`:
+     - Calculate the sum of the quadruplet: `sum = nums[i] + nums[j] + nums[left] + nums[right]`.
+     - If the sum equals the target:
+       - Add `[nums[i], nums[j], nums[left], nums[right]]` to the result.
+       - Move `left` to the right, skipping duplicates.
+       - Move `right` to the left, skipping duplicates.
+     - If the sum is less than the target, move `left` to the right.
+     - If the sum is greater than the target, move `right` to the left.
+7. **Return the Result**: After processing all elements, return the list of quadruplets.

dsa-solutions/lc-solutions/0100-0199/0189-rotate-array.md

@@ -0,0 +1,185 @@
+---
+id: rotate-array
+title: Rotate Array
+sidebar_label: 0189 Rotate Array
+tags:
+  - Array
+  - LeetCode
+  - Java
+  - Python
+  - C++
+description: "This is a solution to the Rotate Array problem on LeetCode."
+---
+
+## Problem Description
+
+Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.
+
+### Examples
+
+**Example 1:**
+
+```
+Input: nums = [1,2,3,4,5,6,7], k = 3
+Output: [5,6,7,1,2,3,4]
+Explanation:
+rotate 1 steps to the right: [7,1,2,3,4,5,6]
+rotate 2 steps to the right: [6,7,1,2,3,4,5]
+rotate 3 steps to the right: [5,6,7,1,2,3,4]
+
+```
+
+**Example 2:**
+
+```
+Input: nums = [-1,-100,3,99], k = 2
+Output: [3,99,-1,-100]
+Explanation: 
+rotate 1 steps to the right: [99,-1,-100,3]
+rotate 2 steps to the right: [3,99,-1,-100]
+```
+
+### Constraints
+
+- $1 <= nums.length <= 105$
+- $-231 <= nums[i] <= 231 - 1$
+- $0 <= k <= 105$
+
+
+## Solution for Candy Distribution Problem
+
+### Intuition And Approach
+
+To rotate an array to the right by k steps, we need to move the last k elements to the front and shift the rest of the elements to the right. A straightforward way to achieve this in-place (without using extra space for another array) is to use the reversal method.
+
+Here is the step-by-step approach:
+
+1. Adjust k:
+
+If k is greater than the length of the array, rotating by k steps is the same as rotating by k % n steps (where n is the length of the array). This is because rotating by the length of the array brings it back to the original position.
+Calculate k = k % n.
+
+2. Reverse the entire array:
+
+By reversing the entire array, the last k elements (which we want to move to the front) will be at the beginning, but in reverse order.
+For example, reversing [1, 2, 3, 4, 5, 6, 7] gives [7, 6, 5, 4, 3, 2, 1].
+
+3. Reverse the first k elements:
+
+The first k elements are now the elements that were originally at the end of the array. Reverse these to restore their original order.
+Continuing the example, reversing the first 3 elements of [7, 6, 5, 4, 3, 2, 1] gives [5, 6, 7, 4, 3, 2, 1].
+
+4. Reverse the remaining n - k elements:
+
+Finally, reverse the rest of the array (from the k-th element to the end) to restore their order.
+In the example, reversing the elements from index 3 to 6 of [5, 6, 7, 4, 3, 2, 1] gives [5, 6, 7, 1, 2, 3, 4].
+
+
+
+#### Code in Different Languages
+
+<Tabs>
+  <TabItem value="Java" label="Java">
+  <SolutionAuthor name="@mahek0620"/>
+   ```java
+       
+    class Solution {
+    public void rotate(int[] nums, int k) {
+        // Ensure k is within the bounds of the array length
+        k = k % nums.length;
+        
+        // Reverse the entire array
+        reverse(nums, 0, nums.length - 1);
+        
+        // Reverse the first k elements
+        reverse(nums, 0, k - 1);
+        
+        // Reverse the remaining elements
+        reverse(nums, k, nums.length - 1);
+    }
+    
+    // Helper function to reverse elements in the array from start to end
+    private void reverse(int[] nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+
+    ```
+  </TabItem>
+  <TabItem value="Python" label="Python">
+  <SolutionAuthor name="@mahek0620"/>
+   ```python
+
+    class Solution(object):
+    def rotate(self, nums, k):
+        k = k % len(nums)
+        
+        # Reverse the entire array
+        self.reverse(nums, 0, len(nums) - 1)
+        
+        # Reverse the first k elements
+        self.reverse(nums, 0, k - 1)
+        
+        # Reverse the remaining elements
+        self.reverse(nums, k, len(nums) - 1)
+    
+    def reverse(self, nums, start, end):
+        while start < end:
+            nums[start], nums[end] = nums[end], nums[start]
+            start += 1
+            end -= 1
+
+    ```
+  </TabItem>
+
+
+<TabItem value="C++" label="C++">
+  <SolutionAuthor name="@mahek0620"/>
+   ```cpp
+
+    #include <vector>
+    using namespace std;
+
+    class Solution {
+    public:
+    void rotate(vector<int>& nums, int k) {
+        // Ensure k is within the bounds of the array length
+        k = k % nums.size();
+        
+        // Reverse the entire array
+        reverse(nums, 0, nums.size() - 1);
+        
+        // Reverse the first k elements
+        reverse(nums, 0, k - 1);
+        
+        // Reverse the remaining elements
+        reverse(nums, k, nums.size() - 1);
+    }
+    
+    private:
+    void reverse(vector<int>& nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+    };
+    ```
+  </TabItem>
+</Tabs>
+
+
+
+## References
+
+- **LeetCode Problem:** [Rotate Array Problem](https://leetcode.com/problems/rotate-array/)
+- **Solution Link:** [Rotate Array Solution on LeetCode](https://leetcode.com/problems/rotate-array/solutions/5273312/rotate-array-solution)
+- **Authors GeeksforGeeks Profile:** [Mahek Patel](https://leetcode.com/u/mahekrpatel611/)