744. Find Smallest Letter Greater Than Target - Easy
阿新 • • 發佈:2018-12-17
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']
'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.
如果沒有比target大的元素,就返回陣列第一個元素
time: O(log(n)), space: O(1)
class Solution { public char nextGreatestLetter(char[] letters, char target) { int left = 0, right = letters.length - 1; while(left + 1 < right) { int mid = left + (right - left) / 2; if(letters[mid] == target) left = mid; else if(letters[mid] < target) left = mid; else right = mid; } if(letters[left] > target) return letters[left]; if(letters[right] > target) return letters[right]; else return letters[0]; } }