Welcome to the daily solving of our PROBLEM OF THE DAY with Yash Dwivedi. We will discuss the entire problem step-by-step and work towards developing an optimized solution. This will not only help you brush up on your concepts of Strings but also build up problem-solving skills.

In this problem, we are given a string n, your task is to find whether it contains an additive sequence or not. A string n contains an additive sequence if its digits can make a sequence of numbers in which every number is addition of previous two numbers. You are required to complete the function which returns true if the string is a valid sequence else returns false. For better understanding check the examples.

Note: A valid string should contain at least three digit to make one additive sequence.

Example :

Input:  
n = "1235813"
Output: 
1
Explanation: 
The given string can be splited into a series of numbers  
where each number is the sum of the previous two numbers: 
1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8, and 5 + 8 = 13. Hence, the output would be 1 (true).

Give the problem a try before going through the video. All the best!!!
Problem Link: https://www.geeksforgeeks.org/problems/additive-sequence/1