shashwat-sahu / cp-dsa

Contribute and add DSA knowledge

CP + DSA

Note: Please fetch upstream before making pull request to update your local repo.
To contribute, add your code / file in respective folders.

Contribution Guide

If you don't have git on your machine, install it.

Fork this repository

Fork this repository by clicking on the fork button on the top of this page. This will create a copy of this repository in your account.

Clone the repository

Now clone the forked repository to your machine. Go to your GitHub account, open the forked repository, click on the code button and then click the copy to clipboard icon.

Open a terminal and run the following git command:

git clone [url you just copied]

where [url you just copied] is the url to this repository (your fork of this project). See the previous steps to obtain the url.

For example:

git clone https://github.com/parteek10/450DSA.git

Create a branch

Change to the repository directory on your computer (if you are not already there):

cd directory-name

Now create a branch using the git checkout command:

git checkout -b your-new-branch-name

For example:

git checkout -b add-hritik

Add new file

If the folder for that topic exist , add a new cpp file with file name as problem number. if the folder for that topic does not exist , create a new one and add the cpp file . For example :

for the problem reverse the array 3 : array->0.cpp   

Make necessary changes and commit those changes

If you go to the project directory and execute the command git status, you'll see there are changes.

Add those changes to the branch you just created using the command:

git add .

Now commit those changes using the git commit command:

git commit -m "Add your committing message here"

Push changes to GitHub

Push your changes using the command git push:

git push origin <add-your-branch-name>

replacing <add-your-branch-name> with the name of the branch you created earlier.

Submit your changes for review

If you go to your repository on GitHub, you'll see a Compare & pull request button. Click on that button.

Now submit the pull request.

cp-dsa's Issues

Valid Parentheses- Complexity O(N)-(by using stack)

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

• Open brackets must be closed by the same type of brackets.
• Open brackets must be closed in the correct order.

Example 1:

Input: s = "{[]}"
Output: true

Templated Stack Class

Stack implementation generic type

Next Greater Element- Complexity O(N)-(using stack)

Description:
Given an array arr[ ] of size N having distinct elements, the task is to find the next greater element for each element of the array in order of their appearance in the array.
Next greater element of an element in the array is the nearest element on the right which is greater than the current element.
If there does not exist next greater of current element, then next greater element for current element is -1. For example, next greater of the last element is always -1.

Example:
Input: N = 4, arr[] = [1 3 2 4]
Output: 3 4 4 -1

Explanation:
In the array, the next larger element to 1 is 3 , 3 is 4 , 2 is 4 and for 4 ,since it doesn't exist, it is -1.

Remove duplicate elements from sorted Array

Given an integer array, nums sorted in non-decreasing order, remove the duplicates in place such that each unique element appears only once.

If there are k elements after removing the duplicates, then the first k elements of nums should hold the final result.

Return array containing all distinct elements after placing the final result in the first k slots of nums.

Example :

Input:
N = 3
Array = {1, 2, 2}
Output: 1 2
Explanation: After removing all the duplicates only two elements i.e., 1 and 2 will remain.

Infix to postfix conversion