#306

Additive Number

expert · 1135 · lc medium +32 · 33.5% accepted · 1,277 likes · top 11%

Description

A string of digits forms an additive sequence if its characters can be split into at least three numbers where every number from the third onward equals the sum of the two preceding it.

Given a digit-only string, 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

Code

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class Solution:
    def isAdditiveNumber(self, num: str) -> bool:

class Solution:
    def isAdditiveNumber(self, num: str) -> bool: