Solution (leetcode-in-java 1.23 API)

java.lang.Object
- g0301_0400.s0306_additive_number.Solution

```
public class Solution
extends Object
```
306 - Additive Number.
Medium

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.

Example 1:

Input: “112358”

Output: true

Explanation:
```
 The digits can form an additive sequence: 1, 1, 2, 3, 5, 8.
 1 + 1 = 2, 1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8 
```
Example 2:

Input: “199100199”

Output: true

Explanation:
```
 The additive sequence is: 1, 99, 100, 199.
 1 + 99 = 100, 99 + 100 = 199 
```
Constraints:
- 1 <= num.length <= 35
- num consists only of digits.
Follow up: How would you handle overflow for very large input integers?

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  boolean isAdditiveNumber(String num)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail

isAdditiveNumber

public boolean isAdditiveNumber(String num)