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:
letters
has a length in range[2, 10000]
.letters
consists of lowercase letters, and contains at least 2 unique letters.target
is a lowercase letter.
思路存ans和看到的最小的char, 如果没有ans, 我们就返回最小的char. O(n)
Code
class Solution: def nextGreatestLetter(self, letters, target): ans = [None] *2 # [0] 记录ans, [1] 记录最小的letters for c in letters: if not ans[1] or ord(c) < ord(ans[1]): ans[1] = c if ord(c) > ord(target) and (not ans[0] or ord(ans[0]) > ord(c)): ans[0] = c return ans[0] if ans[0] else ans[1]