Question: 744. Find Smallest Letter Greater Than Target

Intution:

Time Complexity: $$O(log(n))$$

Space Complexity: $$O(1)$$

Solution:

class Solution {
    public char nextGreatestLetter(char[] letters, char target) {
        int n = letters.length;
        int low = 0;
        int high = n - 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];
    }
}