Solution: Additive Number
Explore how to use backtracking to verify if a numeric string forms a valid additive sequence where each number equals the sum of the previous two. This lesson guides you through recursive checks, pruning strategies, and handling constraints like leading zeros, enabling you to solve this common interview coding pattern efficiently.
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Statement
An additive number is a string whose digits can be partitioned into an additive sequence.
A valid additive sequence contains at least three numbers, where every number after the first two is equal to the sum of the two immediately preceding numbers.
Given a string, num, containing only digits, determine whether it represents an additive number. Return TRUE if a valid additive sequence can be formed from the digits of num, and FALSE otherwise.
Note: Numbers in the additive sequence cannot have leading zeros. For example, the sequences
1, 2, 03and1, 02, 3are both invalid.
Constraints:
num.length...