Problem of The Day: Divide a String Into Groups of Size k

Problem Statement

leetcode problem link

Brute Force [Accepted]

class Solution:
    def divideString(self, s: str, k: int, fill: str) -> List[str]:
        res = []
        for i in range(0,len(s),k):
            curr = s[i:i+k]
            if len(curr) < k:
                curr = ''.join(list(curr) + [fill] * (k - len(curr)))
            res.append(curr[:])
        return res

Editorial

Approach: Search for the starting index of each group

class Solution:
    def divideString(self, s: str, k: int, fill: str) -> List[str]:
        res = []  # grouped string
        n = len(s)
        curr = 0  # starting index of each group
        # split string
        while curr < n:
            res.append(s[curr : curr + k])
            curr += k
        # try to fill in the last group
        res[-1] += fill * (k - len(res[-1]))
        return res

public class Solution {
    public string[] DivideString(string s, int k, char fill) {
        List<string> res = new List<string>();  // grouped string
        int n = s.Length;
        int curr = 0;  // starting index of each group
        // split string
        while (curr < n) {
            int end = Math.Min(curr + k, n);
            res.Add(s.Substring(curr, end - curr));
            curr += k;
        }
        // try to fill in the last group
        string last = res[res.Count - 1];
        if (last.Length < k) {
            last += new string(fill, k - last.Length);
            res[res.Count - 1] = last;
        }
        return res.ToArray();
    }
}