feat: add php solution to lc problem: No.0744 (doocs#953)

Co-authored-by: Yang Libin <contact@yanglibin.info>

Author: Qiu-IT

solution/0700-0799/0744.Find Smallest Letter Greater Than Target/README.md

@@ -201,6 +201,29 @@ impl Solution {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String[] $letters
+     * @param String $target
+     * @return String
+     */
+    function nextGreatestLetter($letters, $target) {
+        $left = 0;
+        $right = count($letters);
+        while ($left <= $right) {
+            $mid = floor($left + ($right - $left) / 2);
+            if ($letters[$mid] > $target) $right = $mid - 1;
+            else $left = $mid + 1;
+        }
+        if ($left >= count($letters)) return $letters[0];
+        else return $letters[$left];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0700-0799/0744.Find Smallest Letter Greater Than Target/README_EN.md

@@ -167,6 +167,29 @@ impl Solution {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String[] $letters
+     * @param String $target
+     * @return String
+     */
+    function nextGreatestLetter($letters, $target) {
+        $left = 0;
+        $right = count($letters);
+        while ($left <= $right) {
+            $mid = floor($left + ($right - $left) / 2);
+            if ($letters[$mid] > $target) $right = $mid - 1;
+            else $left = $mid + 1;
+        }
+        if ($left >= count($letters)) return $letters[0];
+        else return $letters[$left];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0700-0799/0744.Find Smallest Letter Greater Than Target/Solution.php

@@ -0,0 +1,18 @@
+class Solution {
+    /**
+     * @param String[] $letters
+     * @param String $target
+     * @return String
+     */
+    function nextGreatestLetter($letters, $target) {
+        $left = 0;
+        $right = count($letters);
+        while ($left <= $right) {
+            $mid = floor($left + ($right - $left) / 2);
+            if ($letters[$mid] > $target) $right = $mid - 1;
+            else $left = $mid + 1;
+        }
+        if ($left >= count($letters)) return $letters[0];
+        else return $letters[$left];
+    }
+}