Is Find Smallest Letter Greater Than Target easy or hard?

LeetCode classifies this problem as Easy. The main challenge is recognizing that the array is sorted and that the answer may wrap around to the first element, which makes binary search the optimal approach.

Find Smallest Letter Greater Than Target Python/Java solution

Most implementations use a binary search loop with two pointers. The logic is identical across Python, Java, C++, and other languages: adjust the search range based on comparisons and return letters[left % n] after the search completes.

How to solve Find Smallest Letter Greater Than Target in O(log n)?

Use binary search on the sorted letters array. Move the left pointer when the mid character is less than or equal to the target, and move the right pointer otherwise. After the loop, return letters[left % n] to support the wrap‑around case.

What is the best approach for Find Smallest Letter Greater Than Target?

Binary search is the best approach because the letters array is already sorted. By searching for the first element strictly greater than the target, you can find the answer in O(log n) time and O(1) space. The final index is taken modulo the array length to handle the circular condition.

Is Find Smallest Letter Greater Than Target asked at Google/Amazon/Meta?

Binary search pattern problems like this frequently appear in interviews at companies such as Google, Amazon, and Meta. Variants that ask for the first element greater than a target or the next alphabetical character are common in technical screens.

What data structure is used in Find Smallest Letter Greater Than Target?

The problem uses a sorted array of characters. The key algorithmic technique applied on top of the array is binary search to efficiently locate the smallest element greater than the target.

What is the time complexity of Find Smallest Letter Greater Than Target?

The optimal binary search solution runs in O(log n) time because the search space halves every iteration. A simple linear scan solution exists with O(n) time complexity. Both approaches use O(1) additional space.

Description Hints 1 Solution Video 6:40

744. Find Smallest Letter Greater Than Target

Easy59.6% acceptance7 companies

You are given an array of characters letters that is sorted in non-decreasing order, and a character target. There are at least two different characters in letters.

Return the smallest character in letters that is lexicographically greater than target. If such a character does not exist, return the first character in letters.

Example 1:

Input: letters = ["c","f","j"], target = "a"
Output: "c"
Explanation: The smallest character that is lexicographically greater than 'a' in letters is 'c'.

Example 2:

Input: letters = ["c","f","j"], target = "c"
Output: "f"
Explanation: The smallest character that is lexicographically greater than 'c' in letters is 'f'.

Example 3:

Input: letters = ["x","x","y","y"], target = "z"
Output: "x"
Explanation: There are no characters in letters that is lexicographically greater than 'z' so we return letters[0].

Constraints: