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3337. Total Characters in String After Transformations II

Description

You are given a string s consisting of lowercase English letters, an integer t representing the number of transformations to perform, and an array nums of size 26. In one transformation, every character in s is replaced according to the following rules:

  • Replace s[i] with the next nums[s[i] - 'a'] consecutive characters in the alphabet. For example, if s[i] = 'a' and nums[0] = 3, the character 'a' transforms into the next 3 consecutive characters ahead of it, which results in "bcd".
  • The transformation wraps around the alphabet if it exceeds 'z'. For example, if s[i] = 'y' and nums[24] = 3, the character 'y' transforms into the next 3 consecutive characters ahead of it, which results in "zab".

Return the length of the resulting string after exactly t transformations.

Since the answer may be very large, return it modulo 109 + 7.

 

Example 1:

Input: s = "abcyy", t = 2, nums = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2]

Output: 7

Explanation:

  • First Transformation (t = 1):

    • 'a' becomes 'b' as nums[0] == 1
    • 'b' becomes 'c' as nums[1] == 1
    • 'c' becomes 'd' as nums[2] == 1
    • 'y' becomes 'z' as nums[24] == 1
    • 'y' becomes 'z' as nums[24] == 1
    • String after the first transformation: "bcdzz"

  • Second Transformation (t = 2):

    • 'b' becomes 'c' as nums[1] == 1
    • 'c' becomes 'd' as nums[2] == 1
    • 'd' becomes 'e' as nums[3] == 1
    • 'z' becomes 'ab' as nums[25] == 2
    • 'z' becomes 'ab' as nums[25] == 2
    • String after the second transformation: "cdeabab"

  • Final Length of the string: The string is "cdeabab", which has 7 characters.

Example 2:

Input: s = "azbk", t = 1, nums = [2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2]

Output: 8

Explanation:

  • First Transformation (t = 1):

    • 'a' becomes 'bc' as nums[0] == 2
    • 'z' becomes 'ab' as nums[25] == 2
    • 'b' becomes 'cd' as nums[1] == 2
    • 'k' becomes 'lm' as nums[10] == 2
    • String after the first transformation: "bcabcdlm"

  • Final Length of the string: The string is "bcabcdlm", which has 8 characters.

 

Constraints:

  • 1 <= s.length <= 105
  • s consists only of lowercase English letters.
  • 1 <= t <= 109
  • nums.length == 26
  • 1 <= nums[i] <= 25

Solutions

Solution 1

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