Check if Word Equals Summation of Two Words — LeetCode 1880 Python Solution

The problem

The letter value of a letter is its position in the alphabet starting from 0 (i.e. 'a' -> 0, 'b' -> 1, 'c' -> 2, etc.).

Example

Input

firstWord = "acb", secondWord = "cba", targetWord = "cdb"

Output

true

Explanation

The numerical value of firstWord is "acb" -> "021" -> 21.

Python solution

class Solution:
    def isSumEqual(self, firstWord: str, secondWord: str, targetWord: str) -> bool:
        def f(s: str) -> int:
            ans, a = 0, ord("a")
            for c in map(ord, s):
                x = c - a
                ans = ans * 10 + x
            return ans

        return f(firstWord) + f(secondWord) == f(targetWord)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1880. Check if Word Equals Summation of Two Words is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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