# Shifting Letters Problem

## Description

LeetCode Problem 848.

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.

Example 1:

``````1
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Input: s = "abc", shifts = [3,5,9]
Output: "rpl"
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:

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

Constraints:

• 1 <= s.length <= 10^5
• s consists of lowercase English letters.
• shifts.length == s.length
• 0 <= shifts[i] <= 10^9

## Sample C++ Code

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class Solution {
public:
string shiftingLetters(string S, vector<int> shifts) {
for (int i = shifts.size() - 2; i >= 0; i--)
shifts[i] = (shifts[i] + shifts[i + 1]) % 26;
for (int i = 0; i < shifts.size(); i++)
S[i] = (S[i] - 'a' + shifts[i]) % 26 + 'a';
return S;
}
};
``````