Sum of all prefixes of given numeric string
Given string str having N characters representing an integer, the task is to calculate the sum of all possible prefixes of the given string. Example: Input: str = "1225"Output: 1360Explanation: The prefixes of the given string are 1, 12, 122, and 1225 and their sum will be 1 + 12 + 122 + 1225 = 1360