原题
给定一个只包含小写字母的有序数组letters
和一个目标字母 target
,寻找有序数组里面比目标字母大的最小字母。
数组里字母的顺序是循环的。举个例子,如果目标字母target = 'z'
并且有序数组为 letters = ['a', 'b']
,则答案返回 'a'
。
示例:
输入:
letters = ["c", "f", "j"] target = "a"
输出: "c"输入:
letters = ["c", "f", "j"] target = "c"
输出: "f"输入:
letters = ["c", "f", "j"] target = "d"
输出: "f"输入:
letters = ["c", "f", "j"] target = "g"
输出: "j"输入:
letters = ["c", "f", "j"] target = "j"
输出: "c"输入:
letters = ["c", "f", "j"] target = "k"
输出: "c"
注:
letters
长度范围在[2, 10000]
区间内。letters
仅由小写字母组成,最少包含两个不同的字母。- 目标字母
target
是一个小写字母。
解法
思想
二分查找。
代码
class Solution {
public char nextGreatestLetter(char[] letters, char target) {
int start = 0;
int end = letters.length-1;
while(start<end){
int mid = start + (end-start)/2;
if(letters[mid]<=target) start = mid+1;
else end = mid;
}
if(letters[start] <= target) return letters[0];
return letters[start];
}
}
原创文章,作者:彭晨涛,如若转载,请注明出处:https://www.codetool.top/article/leetcode744-%e5%af%bb%e6%89%be%e6%af%94%e7%9b%ae%e6%a0%87%e5%ad%97%e6%af%8d%e5%a4%a7%e7%9a%84%e6%9c%80%e5%b0%8f%e5%ad%97%e6%af%8d/