Count Alternating Subarrays | Super Easy | Leetcode 3031 | Weekly Contest 391 | codestorywithMIK
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This is the 89th Video of our Playlist "Arrays 1D/2D: Popular Interview Problems".
In this video we will try to solve an very good Array Problem which falls under two pointer approach category also :
Count Alternating Subarrays | Super Easy | Leetcode 3031 | Weekly Contest 391 | codestorywithMIK
I will explain the intuition so easily that you will never forget and start seeing this as cakewalk EASYYY.
We will do live coding after explanation and see if we are able to pass all the test cases.
Also, please note that my Github solution link below contains both C++ as well as JAVA code.
Problem Name : Count Alternating Subarrays | Super Easy | Leetcode 3031 | Weekly Contest 391 | codestorywithMIK
Company Tags : will update soon
My solutions on Github(C++ & JAVA) : https://github.com/MAZHARMIK/Interview_DS_Algo/blob/master/Arrays/Two%20Pointer/Count%20Alternating%20Subarrays.cpp
Leetcode Link : https://leetcode.com/problems/count-alternating-subarrays/
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Approach Summary :
Here's a short summary of the approach and logic behind the provided code:
1. **Problem Understanding:**
- We are given an array of integers and asked to count the number of alternating subarrays.
- An alternating subarray is a contiguous subarray where no two adjacent elements have the same value.
2. **Iterative Approach:**
- We iterate through the given array and identify alternating subarrays.
- For each element in the array, we extend the alternating subarray as far as possible by checking adjacent elements.
3. **Counting Subarrays:**
- Once we find an alternating subarray, we calculate the number of subarrays that can be formed from it.
- We use the formula `(len * (len + 1)) / 2` to count the number of subarrays, where `len` is the length of the alternating subarray.
- This formula is derived from the sum of an arithmetic series representing the number of subarrays that can be formed starting from each element in the alternating subarray.
4. **Handling Overflow:**
- Since the number of subarrays can be large, we use a `long` data type to handle larger values.
- This prevents integer overflow during calculations.
5. **Final Output:**
- We return the total count of all alternating subarrays found in the array.
6. **Coding Implementation:**
- The provided code is implemented in both C++ and Java.
- It utilizes loops to iterate through the array and logic to identify alternating subarrays and count them using the formula.
- Proper data types (`long` or `long long`) are used to handle larger values and prevent overflow.
Overall, this approach efficiently solves the problem by iteratively identifying alternating subarrays and counting them using a formula, ensuring correctness and handling large input values.
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✨ Timelines✨
00:00 - Introduction
2:44 - Thought Process & Intuition
7:39 - Proof of the formula
15:51 - More Dry Run
18:05 - Time & Space
18:43 - Coding it up
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