3271. Hash Divided String

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3271. Hash Divided String

Description

You are given a string s of length n and an integer k, where n is a multiple of k. Your task is to hash the string s into a new string called result, which has a length of n / k.

First, divide s into n / k substrings , each with a length of k. Then, initialize result as an empty string.

For each substring in order from the beginning:

  • The hash value of a character is the index of that character in the English alphabet (e.g., 'a' → 0, 'b' → 1, …, 'z' → 25).
  • Calculate the sum of all the hash values of the characters in the substring.
  • Find the remainder of this sum when divided by 26, which is called hashedChar.
  • Identify the character in the English lowercase alphabet that corresponds to hashedChar.
  • Append that character to the end of result.

Return result.

Example 1:

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Input: s = "abcd", k = 2

Output: "bf"

Explanation:

First substring: "ab", 0 + 1 = 1, 1 % 26 = 1, result[0] = 'b'.

Second substring: "cd", 2 + 3 = 5, 5 % 26 = 5, result[1] = 'f'.

Example 2:

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Input: s = "mxz", k = 3

Output: "i"

Explanation:

The only substring: "mxz", 12 + 23 + 25 = 60, 60 % 26 = 8, result[0] = 'i'.

Constraints:

  • 1 <= k <= 100
  • k <= s.length <= 1000
  • s.length is divisible by k.
  • s consists only of lowercase English letters.

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    string stringHash(string s, int k) {
        int n = s.size();
        string res;
        for (int i = 0; i < s.size(); i += k) {
            int sum = 0;
            for (int j = i; j < i + k; j++) {
                sum += s[j] - 'a';
            }
            sum %= 26;
            res.push_back(sum + 'a');
        }
        return res;
    }
};