Additive Number
An additive number is a string whose digits can form an additive sequence.
A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the preceding two.
Given a string containing only digits, return true if it is an additive number or false otherwise.
Note: Numbers in the additive sequence cannot have leading zeros, so sequence 1, 2, 03 or 1, 02, 3 is invalid.
Follow up: How would you handle overflow for very large input integers?
Example 1
Input
num = "112358"Output
trueThe digits can form the additive sequence 1, 1, 2, 3, 5, 8, where each number after the first two is the sum of the preceding two.
Example 2
Input
num = "199100199"Output
trueThe digits can form the additive sequence 1, 99, 100, 199, where 1 + 99 = 100 and 99 + 100 = 199.
Constraints
- 1 <= num.length <= 35
- num consists only of digits.