Calculate Digit Sum of a String — LeetCode 2243 Python Solution

The problem

You are given a string s consisting of digits and an integer k. A round can be completed if the length of s is greater than k.

Example

Input

s = "11111222223", k = 3

Output

"135"

Explanation

- For the first round, we divide s into groups of size 3: "111", "112", "222", and "23".

Python solution

class Solution:
    def digitSum(self, s: str, k: int) -> str:
        while len(s) > k:
            t = []
            n = len(s)
            for i in range(0, n, k):
                x = 0
                for j in range(i, min(i + k, n)):
                    x += int(s[j])
                t.append(str(x))
            s = "".join(t)
        return s

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2243. Calculate Digit Sum of a String 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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