# Find Smallest Letter Greater Than Target Problem

## Description

LeetCode Problem 744.

Given a characters array letters that is sorted in non-decreasing order and a character target, return the smallest character in the array that is larger than target.

Note that the letters wrap around.

- For example, if target == ‘z’ and letters == [‘a’, ‘b’], the answer is ‘a’.

Example 1:

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Input: letters = ["c","f","j"], target = "a"
Output: "c"

Example 2:

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Input: letters = ["c","f","j"], target = "c"
Output: "f"

Example 3:

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Input: letters = ["c","f","j"], target = "d"
Output: "f"

Example 4:

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Input: letters = ["c","f","j"], target = "g"
Output: "j"

Example 5:

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Input: letters = ["c","f","j"], target = "j"
Output: "c"

Constraints:

- 2 <= letters.length <= 10^4
- letters[i] is a lowercase English letter.
- letters is sorted in non-decreasing order.
- letters contains at least two different characters.
- target is a lowercase English letter.

## Sample C++ Code

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class Solution {
public:
char nextGreatestLetter(vector<char>& letters, char target) {
int low = 0;
int high = letters.size()-1;
while (low < high) {
int mid = low + (high - low) / 2;
if (letters[mid] <= target) {
low = mid + 1;
} else {
high = mid;
}
}
return letters[low] > target ? letters[low] : letters[0];
}
};