744. 寻找比目标字母大的最小字母

Go 解决方案
func nextGreatestLetter(letters []byte, target byte) byte {
    left, right := 0, len(letters) - 1
 
    if target >= letters[right] {
        return letters[0]
    }
 
    for ; left < right; {
        mid := (right - left) / 2 + left
        if letters[mid] > target {
            right = mid
        } else {
            left = mid + 1
        }
    }
 
    return letters[left]
}