Given a numeric string str, the task is to calculate the number of substrings with the sum of digits equal to their length.
Input: str = “112112”
Substrings “1”, “1”, “11”, “1”, “1”, “11” satisfy the given condition.
Input: str = “1101112”
Naive Approach: The simplest solution is to generate all substrings of the given string and for each substring, check if its sum is equal to its length or not. For each substring found to be true, increase count.
Time Complexity: O(N3)
Auxiliary Space: O(1)
Efficient Approach: The above approach can be optimized using a Hashmap and keep updating the count of substrings in the Hashmap and print the required count at the end.
Below is the implementation of the above approach:
Time Complexity: O(N)
Auxiliary Space: O(N)
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