feat: added LeetCode problem 1,2

.github/workflows/leetcode_directory_writer.yml

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+# The objective of this GitHub Action is to update the leetcode DIRECTORY.md file (if needed)
+# when doing a git push
+name: leetcode_directory_writer
+on:
+ push:
+ paths:
+ - 'leetcode/src/**.cpp'
+jobs:
+ build:
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/checkout@v3
+ with:
+ fetch-depth: 0
+ - uses: actions/setup-python@v4
+ with:
+ python-version: 3.x
+ - name: Add python dependencies
+ run: |
+ pip install requests
+ - name: Commit and push changes
+ uses: stefanzweifel/git-auto-commit-action@v4
+ id: commit-push
+ with:
+ commit_message: 'docs: updating `leetcode/DIRECTORY.md`'
+ branch: 'leetcode-directory-${{ github.sha }}'
+ create_branch: true

leetcode/README.md

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+# 📚 Contributing 📚
+
+We're glad you're interested in adding C++ LeetCode solutions to the repository.\
+Here we'll be explaining how to contribute to LeetCode solutions properly.
+
+## 💻 Cloning/setting up the project 💻
+
+First off, you'll need to fork the repository [**here**](https://github.com/TheAlgorithms/C-Plus-Plus/fork).\
+Then, you'll need to clone the repository to your local machine.
+
+```bash
+git clone https://github.com/your-username/C-Plus-Plus.git
+```
+
+After that, you'll need to create a new branch for your solution.
+
+```bash
+git checkout -b solution/your-solution-name
+```
+
+## 📝 Adding a new solution 📝
+
+All LeetCode problems can be found [**here**](https://leetcode.com/problemset/all/).\
+If you have a solution to any of these problems (which are not being **repeated**, that's great! Here are the steps:
+
+1. Add a new file in `leetcode/src` with the number of the problem.
+ - For example: if the problem's number is 98, the filename should be `98.cpp`.
+2. Provide a small description of the solution at the top of the file. A function should go below that. For example:
+
+```c
+/**
+ * Return an vector of vector of size returnSize.
+ * The sizes of the vectors are returned as returnColumnSizes vector.
+ * Note: Both returned vector and columnSizes vector must be dynamically allocated, assume caller calls free.
+ */
+```
+
+3. Do not provide a `main` function. Use the required standalone functions instead.
+4. Doxygen documentation isn't used in LeetCode solutions. Simple/small documentation or comments should be fine.
+5. Please include dependency libraries/headers such as `<iostream>`, `<vector>` along with the `Solution` class to the problem. This will help the CI to succeed without the dependency errors.
+
+> **Note**
+> There was a requirement to update the `leetcode/DIRECTORY.md` file with details of the solved problem. It's not required anymore. The information about the problem is fetched automatically throughout the LeetCode API.
+
+## 📦 Committing your changes 📦
+
+Once you're done with adding a new LeetCode solution, it's time we make a pull request.
+
+1. First, stage your changes.
+
+```bash
+git add leetcode/src/98.cpp # Use `git add .` to stage all changes.
+```
+
+2. Then, commit your changes.
+
+```bash
+git commit -m "feat: add LeetCode problem 98" -m "Commit description" # Optional
+```
+
+3. Finally, push your changes to your forked repository.
+
+```bash
+git push origin solution/your-solution-name:solution/your-solution-name
+```
+
+4. You're done now! You just have to make a [**pull request**](https://github.com/TheAlgorithms/C-Plus-Plus/compare). 🎉
+
+If you need any help, don't hesitate to ask and join our [**Discord server**](https://the-algorithms.com/discord)! 🙂

leetcode/src/1.cpp

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+/*
+ * Given an array of integers nums and an integer target, return indices of the
+ * two numbers such that they add up to target.
+ * You may assume that each input would have exactly one solution, and you may not use the same element twice.
+ */
+
+#include <vector>
+#include <unordered_map>
+class Solution {
+public:
+ std::vector<int> twoSum(std::vector<int>& nums, int target) {
+ std::unordered_map<int, int> mp; // value:index
+ std::vector<int> res;
+
+ for (int i = 0; i < nums.size(); i++) {
+ int diff = target - nums[i];
+
+ if (mp.find(diff) != mp.end()) {
+ res.push_back(mp[diff]);
+ res.push_back(i);
+ return res;
+ }
+ mp[nums[i]] = i;
+ }
+ return res;
+ }
+};

leetcode/src/2.cpp

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+/* You are given two non - empty linked lists representing two non - negative integers.
+ * The digits are stored in reverse order, and each of their nodes contains a single digit.
+ * Add the two numbersand return the sum as a linked list.
+ */
+
+#include <memory>
+
+ /*
+ * Definition for singly-linked list.
+ */
+struct ListNode {
+ int val;
+ ListNode *next;
+ explicit ListNode() : val(0), next(nullptr) {}
+ ListNode(int x) : val(x), next(nullptr) {}
+ ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+
+class Solution {
+public:
+ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
+ int carry = 0;
+ std::unique_ptr<ListNode> head(new ListNode(0));
+ ListNode* sum = head.get();
+
+ while(l1 || l2) {
+ int val = carry + (l1 ? l1->val : 0) + (l2 ? l2->val : 0);
+ carry = val/10;
+ sum->next = new ListNode(val%10);
+ sum = sum->next;
+ l1 = (l1 ? l1->next : nullptr);
+ l2 = (l2 ? l2->next : nullptr);
+ }
+ if(carry){
+ sum->next = new ListNode(carry);
+ }
+
+ return head->next;
+}
+};

scripts/leetcode_directory_md.py

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+#!/usr/bin/env python3
+
+from dataclasses import dataclass
+from os import listdir
+from pathlib import Path
+
+import requests
+
+
+@dataclass
+class Task:
+ """The task dataclass. Container for task info"""
+
+ id: str
+ title: str
+ solution: str
+ difficulty: str
+
+
+def fetch_leetcode_folder_tasks(solutions_folder: Path) -> list[Task]:
+ """Fetch leetcode tasks from the Leetcode"""
+
+ # Fetch tasks info from the leetcode API.
+ resp = requests.get("https://leetcode.com/api/problems/algorithms/", timeout=10)
+ content_dict = resp.json()
+
+ raw_tasks_id_dict = {}
+
+ for task in content_dict["stat_status_pairs"]:
+ task_stat = task["stat"]
+ raw_tasks_id_dict[str(task_stat["frontend_question_id"])] = task
+
+ # Generate result tasks info to be inserted into the document
+ tasks_list = []
+
+ difficulty = {1: "Easy", 2: "Medium", 3: "Hard"}
+
+ for fl in listdir(solutions_folder):
+ task_id = fl.split(".")[0]
+
+ raw_task = raw_tasks_id_dict.get(task_id, None)
+ if raw_task is None:
+ continue
+
+ raw_task_stat = raw_task["stat"]
+ tasks_list.append(
+ Task(
+ id=f'{raw_task_stat["frontend_question_id"]}',
+ title=f'[{raw_task_stat["question__title"]}](https://leetcode.com/problems/{raw_task_stat["question__title_slug"]})',
+ solution=f"[C++](./src/{fl})",
+ difficulty=f'{difficulty.get(raw_task["difficulty"]["level"], "")}',
+ )
+ )
+
+ return tasks_list
+
+
+HEADER_ID = "#"
+HEADER_TITLE = "Title"
+HEADER_SOLUTION = "Solution"
+HEADER_DIFFICULTY = "Difficulty"
+SEPARATOR = "-"
+
+
+def print_directory_md(tasks_list: list[Task]) -> None:
+ """Print tasks into the stdout"""
+
+ def get_max_len(get_item):
+ return max(list(map(lambda x: len(get_item(x)), tasks_list)))
+
+ id_max_length = max(get_max_len(lambda x: x.id), len(HEADER_ID))
+ title_max_length = max(get_max_len(lambda x: x.title), len(HEADER_TITLE))
+ solution_max_length = max(get_max_len(lambda x: x.solution), len(HEADER_SOLUTION))
+ difficulty_max_length = max(
+ get_max_len(lambda x: x.difficulty), len(HEADER_DIFFICULTY)
+ )
+
+ def formatted_string(header, title, solution, difficulty):
+ return (
+ f"| {header.rjust(id_max_length)} "
+ + f"| {title.ljust(title_max_length)} "
+ + f"| {solution.ljust(solution_max_length)} "
+ + f"| {difficulty.ljust(difficulty_max_length)} |"
+ )
+
+ tasks_rows = []
+
+ tasks_rows.append(
+ formatted_string(HEADER_ID, HEADER_TITLE, HEADER_SOLUTION, HEADER_DIFFICULTY)
+ )
+ tasks_rows.append(
+ formatted_string(
+ id_max_length * SEPARATOR,
+ title_max_length * SEPARATOR,
+ solution_max_length * SEPARATOR,
+ difficulty_max_length * SEPARATOR,
+ )
+ )
+
+ tasks_list.sort(key=lambda x: int(x.id.strip()))
+
+ for task in tasks_list:
+ tasks_rows.append(
+ formatted_string(task.id, task.title, task.solution, task.difficulty)
+ )
+
+ print(
+ """
+# LeetCode
+
+### LeetCode Algorithm
+"""
+ )
+
+ for item in tasks_rows:
+ print(item)
+
+
+if __name__ == "__main__":
+ top_dir = Path(".")
+ solutions_folder = top_dir / "leetcode" / "src"
+
+ tasks_list = fetch_leetcode_folder_tasks(solutions_folder)
+ print_directory_md(tasks_list)