feat: add php solution to lc problem: No.2190 (#992)

Author: Qiu-IT

solution/2100-2199/2190.Most Frequent Number Following Key In an Array/README.md

@@ -145,6 +145,32 @@ func mostFrequent(nums []int, key int) int {
 
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param Integer[] $nums
+     * @param Integer $key
+     * @return Integer
+     */
+    function mostFrequent($nums, $key) {
+        $max = $maxNum = 0;
+        for ($i = 0; $i < count($nums) - 1; $i++) {
+            if ($nums[$i] == $key) {
+                $hashtable[$nums[$i + 1]] += 1;
+                $tmp = $hashtable[$nums[$i + 1]];
+                if ($tmp > $max) {
+                    $max = $tmp;
+                    $maxNum = $nums[$i + 1];
+                }
+            }
+        }
+        return $maxNum;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/2100-2199/2190.Most Frequent Number Following Key In an Array/README_EN.md

@@ -137,6 +137,32 @@ func mostFrequent(nums []int, key int) int {
 
 ```
 
+### **PHP**
+
+```php
+class Solution {
+    /**
+     * @param Integer[] $nums
+     * @param Integer $key
+     * @return Integer
+     */
+    function mostFrequent($nums, $key) {
+        $max = $maxNum = 0;
+        for ($i = 0; $i < count($nums) - 1; $i++) {
+            if ($nums[$i] == $key) {
+                $hashtable[$nums[$i + 1]] += 1;
+                $tmp = $hashtable[$nums[$i + 1]];
+                if ($tmp > $max) {
+                    $max = $tmp;
+                    $maxNum = $nums[$i + 1];
+                }
+            }
+        }
+        return $maxNum;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/2100-2199/2190.Most Frequent Number Following Key In an Array/Solution.php

@@ -0,0 +1,21 @@
+class Solution {
+    /**
+     * @param Integer[] $nums
+     * @param Integer $key
+     * @return Integer
+     */
+    function mostFrequent($nums, $key) {
+        $max = $maxNum = 0;
+        for ($i = 0; $i < count($nums) - 1; $i++) {
+            if ($nums[$i] == $key) {
+                $hashtable[$nums[$i + 1]] += 1;
+                $tmp = $hashtable[$nums[$i + 1]];
+                if ($tmp > $max) {
+                    $max = $tmp;
+                    $maxNum = $nums[$i + 1];
+                }
+            }
+        }
+        return $maxNum;
+    }
+}