Skip to main content

Shifting Letters

Problem Statement​

You are given a string s of lowercase English letters and an integer array shifts of the same length.

Call the shift() of a letter, the next letter in the alphabet, (wrapping around so that 'z' becomes 'a').

  • For example, shift('a') = 'b', shift('t') = 'u', and shift('z') = 'a'.

Now for each shifts[i] = x, we want to shift the first i + 1 letters of s, x times.

Return the final string after all such shifts to s are applied.

Leetcode Link

Example 1:​

Input: s = "abc", shifts = [3,5,9]
Output: "rpl"
Explanation: We start with "abc".
After shifting the first 1 letters of s by 3, we have "dbc".
After shifting the first 2 letters of s by 5, we have "igc".
After shifting the first 3 letters of s by 9, we have "rpl", the answer.

Example 2:​

Input: s = "aaa", shifts = [1,2,3]
Output: "gfd"

Constraints:​

  • 1 <= s.length <= 105
  • s consists of lowercase English letters.
  • shifts.length == s.length
  • 0 <= shifts[i] <= 109

Code​

Python
class Solution:

    def shiftingLetters(self, s: str, shifts: List[int]) -> str:
        s = list(s)
        alphabet = 'abcdefghijklmnopqrstuvwxyz'
        mydict= {'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'g': 6, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25}
        sums = sum(shifts)
        for i in range(len(s)):
            index = mydict[s[i]]

            index = index + sums
            char = alphabet[index%26]
            sums -= shifts[i]

            s[i] = char

        s = ''.join(s)

        return s