diff --git a/src/main/java/com/cool/ling_cha_mount/binary_search/Num744.java b/src/main/java/com/cool/ling_cha_mount/binary_search/Num744.java
new file mode 100644
index 0000000..987b538
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/binary_search/Num744.java
@@ -0,0 +1,35 @@
+package com.cool.ling_cha_mount.binary_search;
+
+import org.junit.Test;
+
+/**
+ * @author : Cool
+ * @date: 2024/11/11
+ */
+public class Num744 {
+    public char nextGreatestLetter(char[] letters, char target) {
+        int index=binarySearch(letters,(char)((int)target+1));
+        if(index<letters.length){
+            return letters[index];
+        }
+        return letters[0];
+    }
+
+    private int binarySearch(char[] letters,char target){
+        int left=0;
+        int right=letters.length-1;
+        while(left<=right){
+            int mid=(right-left)/2+left;
+            if(letters[mid]>=target){
+                right=mid-1;
+            }else{
+                left=mid+1;
+            }
+        }
+        return left;
+    }
+    @Test
+    public void test(){
+        nextGreatestLetter(new char[]{'c','f','j'},'c');
+    }
+}