Practice Additive Number

Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.

Medium#306

LeetCode Problem

Additive Number

String Backtracking

Problem Statement

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: Example 2: Constraints: Follow up: How would you handle overflow for very large input integers?

Source: Additive Number on LeetCode. Use the original task for its coding environment and submissions.

Examples

# Example 1

Input

"112358"

Output

true

# Example 2

Input

"199100199"

Output

true

Constraints

1 <= num.length <= 35

num consists only of digits.

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