Create FindSmallestLetterGreaterThanTarget.java

ZoranPandovski#3459 Added data-Structure program.

Author: siddhesh-coder

Binary_Search/JAVA/FindSmallestLetterGreaterThanTarget.java

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+//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.
+
+class FindSmallestLetterGreaterThanTarget {
+    public char nextGreatestLetter(char[] letters, char target) {
+        int start = 0; //starting index of an array
+        int end = letters.length-1; //ending index of an array
+        while(start <= end){ //if start is less than or equal to end
+             int mid = start + (end - start)/2; //find middle index so it becomes easy to find target element.
+            if(target < letters[mid]){ //if tareget is less than middle elemant than we will find in left side of array
+                end = mid - 1;
+            }else{ //if tareget is greater than middle elemant than we will find in right side of array
+                start = mid + 1;
+            }
+        } 
+        return letters[start % letters.length];      
+    }
+}