Practice/Meta/Leetcode 744. Find Smallest Letter Greater Than Target

Leetcode 744. Find Smallest Letter Greater Than Target

CodingMust

Problem

You are given a sorted array of lowercase English letters and a target character. Find the smallest character in the array that is strictly greater than the target character.

The array is considered cyclic, meaning if no character is greater than the target, you should return the first character in the array (wrapping around).

The array will always contain at least two characters, and characters may repeat.

Requirements

1. Return the smallest character that is strictly greater than the target
2. If no such character exists, return the first character in the array
3. The solution should efficiently handle the sorted nature of the input
4. Characters in the array may appear multiple times

Constraints

• 2 <= letters.length <= 10^4
• All characters in letters are lowercase English letters
• letters is sorted in non-decreasing order
• letters contains at least two different characters
• target is a lowercase English letter

Examples

Example 1:

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

Example 2:

Input: letters = ['c', 'f', 'j'], target = 'c' Output: 'f' Explanation: We need strictly greater, so 'c' doesn't count. The answer is 'f'.

Example 3:

Input: letters = ['c', 'f', 'j'], target = 'k' Output: 'c' Explanation: No character is greater than 'k', so we wrap around to 'c'.

Example 4:

Input: letters = ['a', 'b', 'b', 'b', 'c', 'e'], target = 'b' Output: 'c' Explanation: Even though 'b' appears multiple times, we need strictly greater, so 'c' is the answer.