Create letter-combination-of-a-phone-number.cpp

letter-combination-of-a-phone-number.cpp

@@ -0,0 +1,33 @@
+class Solution {
+public:
+    void combineLetters(vector<string> &vec, map<char, string> &m, string s, char str[], int curLen) {
+        if (curLen == s.size()) {
+            vec.push_back(str);
+        }
+        for (int i = 0; i < m[s[curLen]].size(); i++) {
+            str[curLen] = m[s[curLen]][i];
+            combineLetters(vec, m, s, str, curLen+1);
+            str[curLen] = '\0';
+        }
+    }
+    vector<string> letterCombinations(string digits) {
+        map<char, string> mapping;
+        mapping['0'] = "";
+        mapping['1'] = "";
+        mapping['2'] = "abc";
+        mapping['3'] = "def";
+        mapping['4'] = "ghi";
+        mapping['5'] = "jkl";
+        mapping['6'] = "mno";
+        mapping['7'] = "pqrs";
+        mapping['8'] = "tuv";
+        mapping['9'] = "wxyz";
+        char str[digits.size()+1];
+        str[digits.size()] = '\0';
+        vector<string> vec;
+        combineLetters(vec, mapping, digits, str, 0);
+        return vec;
+    }
+
+
+};