# 744. Find Smallest Letter Greater Than Target 寻找比目标字母大的最小字母

@TOC

## # 题目描述

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"

Note:

1. letters has a length in range [2, 10000].
2. letters consists of lowercase letters, and contains at least 2 unique letters.
3. target is a lowercase letter.

## # 解题方法

### # 线性扫描

class Solution(object):
def nextGreatestLetter(self, letters, target):
"""
:type letters: List[str]
:type target: str
:rtype: str
"""
for letter in letters:
## 提交了之后发现不用使用ord，字符可以用'>''<'比较大小
if ord(letter) > ord(target):
return letter
return letters[0]

### # 二分查找

class Solution(object):
def nextGreatestLetter(self, letters, target):
"""
:type letters: List[str]
:type target: str
:rtype: str
"""
index = bisect.bisect_right(letters, target)
return letters[index % len(letters)]

## # 日期

2018 年 1 月 23 日 2018 年 11 月 19 日 —— 周一又开始了