添加 0454.四数相加II PHP版本

problems/0454.四数相加II.md

@@ -220,7 +220,37 @@ var fourSumCount = function(nums1, nums2, nums3, nums4) {
 };
 ```
 
-
+PHP:
+```php
+class Solution {
+    /**
+     * @param Integer[] $nums1
+     * @param Integer[] $nums2
+     * @param Integer[] $nums3
+     * @param Integer[] $nums4
+     * @return Integer
+     */
+    function fourSumCount($nums1, $nums2, $nums3, $nums4) {
+        $map = [];
+        foreach ($nums1 as $n1) {
+            foreach ($nums2 as $n2) {
+                $temp = $n1 + $n2;
+                $map[$temp] = isset($map[$temp]) ? $map[$temp]+1 : 1;
+            }
+        }
+        $count = 0;
+        foreach ($nums3 as $n3) {
+            foreach ($nums4 as $n4) {
+                $temp = 0 - $n3 - $n4;
+                if (isset($map[$temp])) {
+                    $count += $map[$temp];
+                }
+            }
+        }
+        return $count;
+    }
+}
+```
 
 
 -----------------------