Create two-sum.php

Author: kamyu104

PHP/two-sum.php

@@ -0,0 +1,21 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+
+    /**
+     * @param Integer[] $nums
+     * @param Integer $target
+     * @return Integer[]
+     */
+    function twoSum($nums, $target) {
+        $lookup = array();
+        foreach ($nums as $i => $x) {
+            if (isset($lookup[$target -$x])) {
+                return [$lookup[$target - $x], $i];
+            }
+            $lookup[$x] = $i;
+        }
+        return [];
+    }
+}