FindSmallestLetterGreaterThanTarget

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Given a list of sorted characters letters containing only lowercase letters, and given a target letter target, find the smallest element in the list that is larger than the given target.

Letters also wrap around. For example, if the target is target = 'z' and letters = ['a', 'b'], the answer is 'a'.

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

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

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

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

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

Input:
letters = ["c", "f", "j"]
target = "k"
Output: "c"
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class Solution {
public:
    char nextGreatestLetter(vector<char>& letters, char target) {   
   int n = letters.size();
        int left = 0,right = n;
        while(left<right){
            int mid = left+(right-left)/2;
            if(letters[mid]>target){
                right = mid;
            }else{
                left = mid+1;
            }
        }
        return letters[left%n];
        }
};