Additive Number Check

Problem

Return True if the digit string can be split into an additive sequence of at least three numbers where every number from the third onward is the sum of the previous two.

Try every possible first and second number, reject numbers with leading zeros unless they are the single digit 0, and grow the sequence until it matches the whole string. Numbers may be very large.

Hint

A leading zero in a multi-digit number immediately disqualifies that split.

Test cases

case 1

in: ["112358"]

expected: true

case 2

in: ["199100199"]

expected: true

case 3

in: ["123"]

expected: true

case 4

in: ["1023"]

expected: false

case 5

in: ["1203"]

expected: false

Starter codePython

def additive_number(num):
    # Your code here
    pass

5 test cases · run your code against them in the editor