feat: add php solution to lc problem: No.1876 (#1014)

Author: Qiu-IT

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/README.md

@@ -99,6 +99,24 @@ function countGoodSubstrings(s: string): number {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String $s
+     * @return Integer
+     */
+    function countGoodSubstrings($s) {
+        $cnt = 0;
+        for ($i = 0; $i < strlen($s) - 2; $i++) {
+            if ($s[$i] != $s[$i + 1] && $s[$i] != $s[$i + 2] && $s[$i + 1] != $s[$i + 2]) $cnt++;
+        }
+        return $cnt++;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/README_EN.md

@@ -89,6 +89,24 @@ function countGoodSubstrings(s: string): number {
 }
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param String $s
+     * @return Integer
+     */
+    function countGoodSubstrings($s) {
+        $cnt = 0;
+        for ($i = 0; $i < strlen($s) - 2; $i++) {
+            if ($s[$i] != $s[$i + 1] && $s[$i] != $s[$i + 2] && $s[$i + 1] != $s[$i + 2]) $cnt++;
+        }
+        return $cnt++;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/Solution.php

@@ -0,0 +1,13 @@
+class Solution {
+    /**
+     * @param String $s
+     * @return Integer
+     */
+    function countGoodSubstrings($s) {
+        $cnt = 0;
+        for ($i = 0; $i < strlen($s) - 2; $i++) {
+            if ($s[$i] != $s[$i + 1] && $s[$i] != $s[$i + 2] && $s[$i + 1] != $s[$i + 2]) $cnt++;
+        }
+        return $cnt++;
+    }
+}