You are given a string s and an integer t, representing the number of transformations to perform. In one transformation, every character in s is replaced according to the following rules:
'z', replace it with the string "ab".'a' is replaced with 'b', 'b' is replaced with 'c', and so on.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
Output: 7
Explanation:
<ul>
<li><code>'a'</code> becomes <code>'b'</code></li>
<li><code>'b'</code> becomes <code>'c'</code></li>
<li><code>'c'</code> becomes <code>'d'</code></li>
<li><code>'y'</code> becomes <code>'z'</code></li>
<li><code>'y'</code> becomes <code>'z'</code></li>
<li>String after the first transformation: <code>"bcdzz"</code></li>
</ul>
</li>
<li><strong>Second Transformation (t = 2)</strong>:
<ul>
<li><code>'b'</code> becomes <code>'c'</code></li>
<li><code>'c'</code> becomes <code>'d'</code></li>
<li><code>'d'</code> becomes <code>'e'</code></li>
<li><code>'z'</code> becomes <code>"ab"</code></li>
<li><code>'z'</code> becomes <code>"ab"</code></li>
<li>String after the second transformation: <code>"cdeabab"</code></li>
</ul>
</li>
<li><strong>Final Length of the string</strong>: The string is <code>"cdeabab"</code>, which has 7 characters.</li>
Example 2:
Input: s = "azbk", t = 1
Output: 5
Explanation:
<ul>
<li><code>'a'</code> becomes <code>'b'</code></li>
<li><code>'z'</code> becomes <code>"ab"</code></li>
<li><code>'b'</code> becomes <code>'c'</code></li>
<li><code>'k'</code> becomes <code>'l'</code></li>
<li>String after the first transformation: <code>"babcl"</code></li>
</ul>
</li>
<li><strong>Final Length of the string</strong>: The string is <code>"babcl"</code>, which has 5 characters.</li>
Constraints:
1 <= s.length <= 105s consists only of lowercase English letters.1 <= t <= 105