Again i think it is backtracking, yeah,cool

Author: ChSatyaSavith

17. Letter Combinations of a Phone Number.cpp

@@ -0,0 +1,38 @@
+class Solution {
+public:
+    vector<string> output;
+    void backtrack(int start,map<char,string> phone,string temp,string digits)
+    {
+        if(start>=digits.length())
+        {
+            output.push_back(temp);
+            return;
+        }
+        for(auto x:phone[digits[start]])
+        {
+            temp.push_back(x);
+            backtrack(start+1,phone,temp,digits);
+            temp.pop_back();
+
+        }
+    }
+    vector<string> letterCombinations(string digits) 
+    {
+        if(digits=="")
+        {
+            return output;
+        }
+        map<char,string> phone;
+        phone['2'] = "abc";
+        phone['3'] = "def";
+        phone['4'] = "ghi";
+        phone['5'] = "jkl";
+        phone['6'] = "mno";
+        phone['7'] = "pqrs";
+        phone['8'] = "tuv";
+        phone['9'] = "wxyz";
+        string temp = "";
+        backtrack(0,phone,temp,digits);
+        return output;
+    }
+};