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### by Sumit Chourasia | Oct 03, 2020 | Category :coding | Tags : algorithmbinary-searchdata-structureeasyleetcode #### Find Smallest Letter Greater Than Target - Array - Easy - LeetCode

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'], the answer is '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.

``````public class Solution {
public char NextGreatestLetter(char[] letters, char target) {
if(target>=letters[letters.Length-1]){
return letters;
}

int low = 0;
int high = letters.Length-1;
while(low<high){
int mid = low + (high-low)/2;
if(letters[mid]<=target){
low = mid+1;
}
else{
high=mid;
}

}

return letters[high];
}
}``````

Time Complexity: O(logn)

Space Complexity: O(1)