All DSA Problems

Author: alisamad1

.gitignore

@@ -7,4 +7,7 @@
 *.o
 
 # Ignore temporary files created by VS Code extensions
-tempCodeRunnerFile.cpp
+tempCodeRunnerFile.cpp
+
+# Ignore build directories
+build/

Recursion/README.md

@@ -0,0 +1,120 @@
+
+# C++ Data Structures & Algorithms (DSA) + LeetCode Solutions 🔥🔥🔥
+
+![Language](https://img.shields.io/badge/Language-C%2B%2B-blue.svg)
+![License](https://img.shields.io/badge/License-MIT-green.svg)
+![Repo Status](https://img.shields.io/badge/Status-Active-brightgreen.svg)
+
+Welcome to **C++ DSA & LeetCode Solutions**—your all-in-one resource for mastering data structures, algorithms and acing coding interviews!  
+Welcome to **C++ DSA & LeetCode Solutions**—your all-in-one resource for mastering data structures, algorithms and acing coding interviews!
+This repository features clean, well-documented C++ implementations covering foundational CS concepts *and* a growing library of LeetCode problem solutions.
+
+---
+
+## 🚩 Features
+
+- **Core DSA modules:** Binary search, sorting, arrays, and more.
+- **Extensive LeetCode practice:** Solutions mapped by problem number, ideal for interviews and self-study.
+- **Clear folder structure:** Easily find what you need, whether it’s theory or practice.
+- **Beginner-friendly:** Accessible explanations and simple build instructions.
+
+---
+
+## 📁 Repository Structure
+
+DSA/
+├── Leetcode_Practice_Questions/ # LeetCode solutions
+│ ├── LC_1.cpp
+│ ├── LC_2.cpp
+│ └── README.md
+├── binarysearch.cpp # Core algorithms/data structures
+├── sort_0_&_1.cpp
+├── ...
+└── README.md # Start here!
+
+```
+cppdsa/
+├── Leetcode_Practice_Questions/  # LeetCode solutions
+│   ├── LC_1.cpp
+│   ├── LC_2.cpp
+│   └── ...
+├── binarysearch.cpp              # Core algorithms/data structures
+├── sort_0_&_1.cpp
+└── README.md                     # Start here!
+```
+
+### Highlights
+
+- **Leetcode_Practice_Questions**:  
+- **Leetcode_Practice_Questions**:
+  Organized, numbered solutions with a focused [README](./Leetcode_Practice_Questions/README.md).
+
+- **Core DSA files**:  
+  Example:  
+  - `binarysearch.cpp`: Classic binary search implementation  
+  - `sort_0_&_1.cpp`: Fast 0/1 segregation in arrays  
+- **Core DSA files**:
+  Example:
+  - `binarysearch.cpp`: Classic binary search implementation
+  - `sort_0_&_1.cpp`: Fast 0/1 segregation in arrays
+  - (More coming soon!)
+
+---
+
+## 🧑‍💻 Usage & Getting Started
+
+1. **Clone the Repository**
+git clone https://github.com/alisamad1/DSA.git
+   ```bash
+   git clone https://github.com/your-username/your-repo-name.git
+   ```
+2. **Enter the Directory**
+cd DSA
+   ```bash
+   cd cppdsa
+   ```
+3. **Compile & Run Any File**
+- With `g++` (example for binarysearch):
+  ```
+  g++ binarysearch.cpp -o binarysearch
+  ./binarysearch
+  ```
+   ```bash
+   g++ binarysearch.cpp -o binarysearch
+   ./binarysearch
+   ```
+- Or open files using your favorite C++ IDE (e.g., VS Code, CLion).
+
+---
+
+## ✍️ Contributing
+
+Contributions, bug reports, and suggestions are welcome!  
+Whether you spot a typo, want to add a new algorithm, or have ideas for improvement, just open an issue or pull request.
+Contributions, bug reports, and suggestions are welcome!
+Whether you spot a typo, want to add a new algorithm, or have ideas for improvement, just open an issue or pull request on the new repository.
+
+---
+
+## 💡 Why Use This Repository?
+
+- **Exam & Interview Prep:** Spot-on for students and job-seekers.
+- **Learning by Examples:** Study code, understand logic, and solve problems hands-on.
+- **Open Source:** Freely use and extend under the MIT License.
+
+---
+
+## 📫 Contact
+
+Questions? Ideas?  
+Questions? Ideas?
+Let’s connect!
+
+- **LinkedIn:** https://www.linkedin.com/in/ali-samad-841b11301/
+- **Email:** aliussamad@gmail.com
+
+---
+
+## ⭐ Support
+
+If this project helps you, please ⭐️ this repo and share it to support more learners!

Recursion/letter_combination_of_string.cpp

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+#include <iostream>
+#include <vector>
+#include <string>
+#include <unordered_map>
+using namespace std;
+class Solution {
+    vector<string> result;  
+    void solve(int idx, string &digits, string &temp, unordered_map<char, string> &mp) {
+        if (idx >= digits.length()) {
+            result.push_back(temp);
+            return;
+        }   
+        char ch = digits[idx];
+        string str = mp[ch];
+        for (int i = 0; i < str.length(); i++) {
+            temp.push_back(str[i]);
+            solve(idx + 1, digits, temp, mp);
+            temp.pop_back();
+        }
+    }
+public:
+    vector<string> letterCombinations(string digits) {
+        result.clear();
+        if (digits.length() == 0) {
+            return {};
+        }
+        unordered_map<char, string> mp;
+        mp['2'] = "abc";
+        mp['3'] = "def";
+        mp['4'] = "ghi";
+        mp['5'] = "jkl";
+        mp['6'] = "mno";
+        mp['7'] = "pqrs";
+        mp['8'] = "tuv";
+        mp['9'] = "wxyz";
+        string temp = "";
+        solve(0, digits, temp, mp);
+        return result;
+    }
+};
+int main() {
+    Solution sol;
+    string digits;
+    cout << "Enter digits: ";
+    cin >> digits;
+    vector<string> combos = sol.letterCombinations(digits);
+    cout << "Letter combinations are:" << endl;
+    for (const string &combo : combos) {
+        cout << combo << endl;
+    }
+    return 0;
+}

Recursion/subsequence_of_string.cpp

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+#include <iostream>
+#include <vector>
+#include <string>
+#include <algorithm>
+using namespace std;
+void solve(vector<string>& ans, string output, string str, int index) {
+    if (index >= str.length()) {
+        if (output.length() > 0) {
+            ans.push_back(output);
+        }
+        return;
+    }
+    solve(ans, output, str, index + 1);
+    solve(ans, output + str[index], str, index + 1);
+}
+vector<string> subsequences(string str) {
+    vector<string> ans;
+    string output = "";
+    solve(ans, output, str, 0);
+    sort(ans.begin(), ans.end());
+    return ans;
+}
+int main() {
+    string s;
+    cout << "Enter a string: ";
+    cin >> s;
+    vector<string> result = subsequences(s);
+    cout << "Subsequences are: " << endl;
+    for (const string& sub : result) {
+        cout << sub << endl;
+    }
+    return 0;
+}

Recursion/subsets.cpp

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+#include <iostream>
+#include <vector>
+#include <algorithm> 
+using namespace std;
+void createSubset(vector<int>& nums, int index, vector<vector<int>>& res, vector<int>& subset){
+    if(index == nums.size()){
+        res.push_back(subset);
+        return;
+    }
+    subset.push_back(nums[index]);
+    createSubset(nums,index+1, res, subset);
+    subset.pop_back();
+    createSubset(nums,index+1, res, subset);
+}
+vector<vector<int>> subsets(vector<int>& nums) {
+    vector<vector<int>> res;
+    vector<int> subset;
+    createSubset(nums,0, res, subset);
+    return res;
+}
+int main() {
+    vector<int> nums = {1, 2, 3};
+    vector<vector<int>> result = subsets(nums);
+    cout << "All subsets:" << endl;
+    for (const auto& s : result) {
+        cout << "[";
+        for (size_t i = 0; i < s.size(); ++i) {
+            cout << s[i];
+            if (i < s.size() - 1) {
+                cout << ", ";
+            }
+        }
+        cout << "]" << endl;
+    }
+    vector<int> nums2 = {0};
+    vector<vector<int>> result2 = subsets(nums2);
+    cout << "\nAll subsets for {0}:" << endl;
+    for (const auto& s : result2) {
+        cout << "[";
+        for (size_t i = 0; i < s.size(); ++i) {
+            cout << s[i];
+            if (i < s.size() - 1) {
+                cout << ", ";
+            }
+        }
+        cout << "]" << endl;
+    }
+    return 0;
+}