Add solution 137.

Author: javadev

src/Algorithms/0137.single-number-ii/single-number-ii.php

@@ -0,0 +1,36 @@
+class Solution {
+
+    /**
+     * @param Integer[] $nums
+     * @return Integer
+     */
+    function singleNumber($nums) {
+        sort($nums); 
+        
+        $result = -1; 
+        $found = false; 
+        $i = 0; 
+        
+        while($found == false){
+            $found = false;
+			
+            if($i == count($nums) - 1){
+                $result = $nums[$i]; 
+                $found = true; 
+                break;
+            }
+			//if its next one, then we know three more of same number exist
+            if($nums[$i] == $nums[$i+1]){
+                $i+=3; 
+                continue; 
+            }
+            else{
+			//if not equal to the one next to it, we've found it. 
+                $result = $nums[$i]; 
+                $found = true; 
+                break;
+            }
+        }
+        return $result; 
+    }
+}