744-find-smallest-letter-greater-than-target.md

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

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:

1. letters长度范围在[2, 10000]区间内。
2. letters 仅由小写字母组成，最少包含两个不同的字母。
3. 目标字母target 是一个小写字母。

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题目标签：Binary Search

题目链接：LeetCode / LeetCode中国

题解

Language	Runtime	Memory
java	0 ms	40.3 MB

class Solution {
    public char nextGreatestLetter(char[] letters, char target) {
        int l = 0, r = letters.length - 1;
        while (l < r) {
            int mid = l + r >> 1;
            if (letters[mid] > target) r = mid;
            else l = mid + 1;
        }
        return letters[l] <= target ? letters[0] : letters[l];
    }
}