Create phonenum-letter-comb.py

finds all combinations of letters that can be formed turning a phone number into each numbers character representation. Very slow for longer nums as it increases exponentially

phonenum-letter-comb.py

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+class Solution:
+    def letterCombinations(self, digits: str) -> List[str]:
+        numflag = (digits != "") #Checks if digits not empty
+        inp = [digits]
+        output = []
+        endindex = 0
+        tempdigit = "2"
+        tempstr = ""
+        tempindex = 0
+        while numflag:
+            numflag = False
+            inp = inp[endindex:]
+            print(inp)
+            endindex = len(inp)
+            for s in inp:
+                if s[-1].isdigit():
+                    for i in range(len(s)):
+                        if s[i].isdigit():
+                            numflag = True
+                            tempdigit = s[i]
+                            tempindex = i
+                            break
+                    tempstr = self.chToStr(tempdigit)
+                    for tempch in tempstr:
+                        inp.append(s[:tempindex] + tempch + s[tempindex+1:])
+                else:
+                    if s not in output:
+                        output.append(s)
+        return output
+
+    def chToStr(self, ch):
+        if ch == "2":
+            return "abc"
+        elif ch == "3":
+            return "def"
+        elif ch == "4":
+            return "ghi"
+        elif ch == "5":
+            return "jkl"
+        elif ch == "6":
+            return "mno"
+        elif ch == "7":
+            return "pqrs"
+        elif ch == "8":
+            return "tuv"
+        elif ch == "9":
+            return "wxyz"