feat: add php solution to lc problem: No.1945 (doocs#985)

Author: Qiu-IT

solution/1900-1999/1945.Sum of Digits of String After Convert/README.md

@@ -186,6 +186,34 @@ impl Solution {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String $s
+     * @param Integer $k
+     * @return Integer
+     */
+    function getLucky($s, $k) {
+        $rs = "";
+        for ($i = 0; $i < strlen($s); $i++) {
+            $num = ord($s[$i]) - 96;
+            $rs = $rs.strval($num);
+        }
+        while ($k != 0) {
+            $sum = 0;
+            for ($j = 0; $j < strlen($rs); $j++) {
+                $sum += intval($rs[$j]);
+            }
+            $rs = strval($sum);
+            $k--;
+        }
+        return intval($rs);
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1900-1999/1945.Sum of Digits of String After Convert/README_EN.md

@@ -177,6 +177,34 @@ impl Solution {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String $s
+     * @param Integer $k
+     * @return Integer
+     */
+    function getLucky($s, $k) {
+        $rs = "";
+        for ($i = 0; $i < strlen($s); $i++) {
+            $num = ord($s[$i]) - 96;
+            $rs = $rs.strval($num);
+        }
+        while ($k != 0) {
+            $sum = 0;
+            for ($j = 0; $j < strlen($rs); $j++) {
+                $sum += intval($rs[$j]);
+            }
+            $rs = strval($sum);
+            $k--;
+        }
+        return intval($rs);
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1900-1999/1945.Sum of Digits of String After Convert/Solution.php

@@ -0,0 +1,23 @@
+class Solution {
+    /**
+     * @param String $s
+     * @param Integer $k
+     * @return Integer
+     */
+    function getLucky($s, $k) {
+        $rs = "";
+        for ($i = 0; $i < strlen($s); $i++) {
+            $num = ord($s[$i]) - 96;
+            $rs = $rs.strval($num);
+        }
+        while ($k != 0) {
+            $sum = 0;
+            for ($j = 0; $j < strlen($rs); $j++) {
+                $sum += intval($rs[$j]);
+            }
+            $rs = strval($sum);
+            $k--;
+        }
+        return intval($rs);
+    }
+}